Serde performance: where the time goes
Profiling serialization hot paths. This post digs into the topic, drawing on recent discussion from Hacker News, Reddit, and the wider community.
The conversation that prompted this post is linked in the sources. I have tried to capture the substance of the discussion rather than just summarize it, because the comments are usually where the real insight lives.
What happened
Compile times remain the single most common complaint from new Rust developers, and the compiler team has been steadily attacking them. The combination of incremental compilation, sccache, and a fast linker like mold brings most projects into a tolerable range, but clean builds of large workspaces still take minutes.
The standard library is deliberately small. Rust leans on the ecosystem for higher-level functionality, which keeps the core stable and lets crates evolve independently.
Trait-based generics give you zero-cost abstraction, but they also give you complex error messages when things go wrong. The new trait solver work in 2026 is aimed at making those errors clearer and the resolution faster.
Error handling via Result and Option is verbose but honest. Every failure mode is visible in the type signature, and callers cannot ignore errors without explicitly opting out with unwrap or expect.
Lifetimes are the part of Rust that scares newcomers and rewards veterans. Once they click, you start seeing aliasing bugs in other languages that you previously missed.
Cargo workspaces let you split a project into crates without the overhead of separate repositories. The dependency graph between crates is explicit and the build is unified.
Error handling via Result and Option is verbose but honest. Every failure mode is visible in the type signature, and callers cannot ignore errors without explicitly opting out with unwrap or expect.
Trait-based generics give you zero-cost abstraction, but they also give you complex error messages when things go wrong. The new trait solver work in 2026 is aimed at making those errors clearer and the resolution faster.
The standard library is deliberately small. Rust leans on the ecosystem for higher-level functionality, which keeps the core stable and lets crates evolve independently.
Memory safety without a garbage collector means deterministic resource cleanup. Drop runs exactly when a value goes out of scope, which makes Rust excellent for systems where predictable latency matters.
Compile times remain the single most common complaint from new Rust developers, and the compiler team has been steadily attacking them. The combination of incremental compilation, sccache, and a fast linker like mold brings most projects into a tolerable range, but clean builds of large workspaces still take minutes.
Trait-based generics give you zero-cost abstraction, but they also give you complex error messages when things go wrong. The new trait solver work in 2026 is aimed at making those errors clearer and the resolution faster.
Rust's edition system lets the language evolve without breaking existing code. Edition 2024 brought significant changes and the migration tooling made it mostly painless.
The standard library is deliberately small. Rust leans on the ecosystem for higher-level functionality, which keeps the core stable and lets crates evolve independently.
The borrow checker is not your enemy. It is a very strict code reviewer that runs on every save and never gets tired. Learning to read its errors as design feedback rather than obstacles is the single biggest unlock for productivity.
Why it matters
Unsafe Rust is a feature, not a bug. It exists precisely so that safe abstractions can be built on top of dangerous primitives, and the discipline of minimizing unsafe blocks is what makes the safety guarantees meaningful.
Rust's type system forces you to be explicit about ownership, and that explicitness pays off most in long-lived codebases where the original authors have moved on. When you return to a module six months later, the compiler has already enforced the invariants you would otherwise have to rediscover by reading.
Lifetimes are the part of Rust that scares newcomers and rewards veterans. Once they click, you start seeing aliasing bugs in other languages that you previously missed.
Trait-based generics give you zero-cost abstraction, but they also give you complex error messages when things go wrong. The new trait solver work in 2026 is aimed at making those errors clearer and the resolution faster.
Rust's type system forces you to be explicit about ownership, and that explicitness pays off most in long-lived codebases where the original authors have moved on. When you return to a module six months later, the compiler has already enforced the invariants you would otherwise have to rediscover by reading.
Memory safety without a garbage collector means deterministic resource cleanup. Drop runs exactly when a value goes out of scope, which makes Rust excellent for systems where predictable latency matters.
Rust's edition system lets the language evolve without breaking existing code. Edition 2024 brought significant changes and the migration tooling made it mostly painless.
Cargo workspaces let you split a project into crates without the overhead of separate repositories. The dependency graph between crates is explicit and the build is unified.
Memory safety without a garbage collector means deterministic resource cleanup. Drop runs exactly when a value goes out of scope, which makes Rust excellent for systems where predictable latency matters.
Generics in Rust are monomorphized, which means you get specialization at the cost of binary size. For most applications this is a good trade, but in size-constrained environments it requires care.
Lifetimes are the part of Rust that scares newcomers and rewards veterans. Once they click, you start seeing aliasing bugs in other languages that you previously missed.
Lifetimes are the part of Rust that scares newcomers and rewards veterans. Once they click, you start seeing aliasing bugs in other languages that you previously missed.
Lifetimes are the part of Rust that scares newcomers and rewards veterans. Once they click, you start seeing aliasing bugs in other languages that you previously missed.
Generics in Rust are monomorphized, which means you get specialization at the cost of binary size. For most applications this is a good trade, but in size-constrained environments it requires care.
The borrow checker is not your enemy. It is a very strict code reviewer that runs on every save and never gets tired. Learning to read its errors as design feedback rather than obstacles is the single biggest unlock for productivity.
Practical takeaways
- Error handling via Result and Option is verbose but honest.
- Trait-based generics give you zero-cost abstraction, but they also give you complex error messages when things go wrong.
- Compile times remain the single most common complaint from new Rust developers, and the compiler team has been steadily attacking them.
- Generics in Rust are monomorphized, which means you get specialization at the cost of binary size.
- Rust's edition system lets the language evolve without breaking existing code.
- Error handling via Result and Option is verbose but honest.
- The standard library is deliberately small.
- Error handling via Result and Option is verbose but honest.
- Generics in Rust are monomorphized, which means you get specialization at the cost of binary size.
- Macros in Rust are powerful but should be used sparingly.
Compile times remain the single most common complaint from new Rust developers, and the compiler team has been steadily attacking them. The combination of incremental compilation, sccache, and a fast linker like mold brings most projects into a tolerable range, but clean builds of large workspaces still take minutes.
Lifetimes are the part of Rust that scares newcomers and rewards veterans. Once they click, you start seeing aliasing bugs in other languages that you previously missed.
Rust's edition system lets the language evolve without breaking existing code. Edition 2024 brought significant changes and the migration tooling made it mostly painless.
Unsafe Rust is a feature, not a bug. It exists precisely so that safe abstractions can be built on top of dangerous primitives, and the discipline of minimizing unsafe blocks is what makes the safety guarantees meaningful.
Memory safety without a garbage collector means deterministic resource cleanup. Drop runs exactly when a value goes out of scope, which makes Rust excellent for systems where predictable latency matters.
Unsafe Rust is a feature, not a bug. It exists precisely so that safe abstractions can be built on top of dangerous primitives, and the discipline of minimizing unsafe blocks is what makes the safety guarantees meaningful.
Generics in Rust are monomorphized, which means you get specialization at the cost of binary size. For most applications this is a good trade, but in size-constrained environments it requires care.
Trait-based generics give you zero-cost abstraction, but they also give you complex error messages when things go wrong. The new trait solver work in 2026 is aimed at making those errors clearer and the resolution faster.
Error handling via Result and Option is verbose but honest. Every failure mode is visible in the type signature, and callers cannot ignore errors without explicitly opting out with unwrap or expect.
Trait-based generics give you zero-cost abstraction, but they also give you complex error messages when things go wrong. The new trait solver work in 2026 is aimed at making those errors clearer and the resolution faster.
Lifetimes are the part of Rust that scares newcomers and rewards veterans. Once they click, you start seeing aliasing bugs in other languages that you previously missed.
Unsafe Rust is a feature, not a bug. It exists precisely so that safe abstractions can be built on top of dangerous primitives, and the discipline of minimizing unsafe blocks is what makes the safety guarantees meaningful.
Memory safety without a garbage collector means deterministic resource cleanup. Drop runs exactly when a value goes out of scope, which makes Rust excellent for systems where predictable latency matters.
Cargo is the secret weapon. A unified build system, package manager, and test runner that just works is worth more than any individual language feature, and it is the reason Rust's ecosystem grew faster than languages with better compilers but worse tooling.
The borrow checker is not your enemy. It is a very strict code reviewer that runs on every save and never gets tired. Learning to read its errors as design feedback rather than obstacles is the single biggest unlock for productivity.
Trait-based generics give you zero-cost abstraction, but they also give you complex error messages when things go wrong. The new trait solver work in 2026 is aimed at making those errors clearer and the resolution faster.
Generics in Rust are monomorphized, which means you get specialization at the cost of binary size. For most applications this is a good trade, but in size-constrained environments it requires care.
Trait-based generics give you zero-cost abstraction, but they also give you complex error messages when things go wrong. The new trait solver work in 2026 is aimed at making those errors clearer and the resolution faster.
Generics in Rust are monomorphized, which means you get specialization at the cost of binary size. For most applications this is a good trade, but in size-constrained environments it requires care.
Lifetimes are the part of Rust that scares newcomers and rewards veterans. Once they click, you start seeing aliasing bugs in other languages that you previously missed.
Sources
This post is informed by discussion on serde.rs and related threads on Hacker News and Reddit. Primary source: https://serde.rs/.
Cargo is the secret weapon. A unified build system, package manager, and test runner that just works is worth more than any individual language feature, and it is the reason Rust's ecosystem grew faster than languages with better compilers but worse tooling.
Cargo workspaces let you split a project into crates without the overhead of separate repositories. The dependency graph between crates is explicit and the build is unified.
Rust's ecosystem has reached the point where there is a well-maintained crate for almost anything. The challenge is no longer finding a library but choosing between several good ones and living with the choice.
The borrow checker is not your enemy. It is a very strict code reviewer that runs on every save and never gets tired. Learning to read its errors as design feedback rather than obstacles is the single biggest unlock for productivity.
Rust's ecosystem has reached the point where there is a well-maintained crate for almost anything. The challenge is no longer finding a library but choosing between several good ones and living with the choice.
The borrow checker is not your enemy. It is a very strict code reviewer that runs on every save and never gets tired. Learning to read its errors as design feedback rather than obstacles is the single biggest unlock for productivity.
Unsafe Rust is a feature, not a bug. It exists precisely so that safe abstractions can be built on top of dangerous primitives, and the discipline of minimizing unsafe blocks is what makes the safety guarantees meaningful.
Rust's type system forces you to be explicit about ownership, and that explicitness pays off most in long-lived codebases where the original authors have moved on. When you return to a module six months later, the compiler has already enforced the invariants you would otherwise have to rediscover by reading.
The standard library is deliberately small. Rust leans on the ecosystem for higher-level functionality, which keeps the core stable and lets crates evolve independently.
Unsafe Rust is a feature, not a bug. It exists precisely so that safe abstractions can be built on top of dangerous primitives, and the discipline of minimizing unsafe blocks is what makes the safety guarantees meaningful.
Cargo is the secret weapon. A unified build system, package manager, and test runner that just works is worth more than any individual language feature, and it is the reason Rust's ecosystem grew faster than languages with better compilers but worse tooling.
Macros in Rust are powerful but should be used sparingly. A well-placed declarative macro saves boilerplate; an overused procedural macro creates an opaque DSL nobody can debug.
Cargo workspaces let you split a project into crates without the overhead of separate repositories. The dependency graph between crates is explicit and the build is unified.
Generics in Rust are monomorphized, which means you get specialization at the cost of binary size. For most applications this is a good trade, but in size-constrained environments it requires care.
Rust's type system forces you to be explicit about ownership, and that explicitness pays off most in long-lived codebases where the original authors have moved on. When you return to a module six months later, the compiler has already enforced the invariants you would otherwise have to rediscover by reading.
Macros in Rust are powerful but should be used sparingly. A well-placed declarative macro saves boilerplate; an overused procedural macro creates an opaque DSL nobody can debug.
Unsafe Rust is a feature, not a bug. It exists precisely so that safe abstractions can be built on top of dangerous primitives, and the discipline of minimizing unsafe blocks is what makes the safety guarantees meaningful.
Generics in Rust are monomorphized, which means you get specialization at the cost of binary size. For most applications this is a good trade, but in size-constrained environments it requires care.
Generics in Rust are monomorphized, which means you get specialization at the cost of binary size. For most applications this is a good trade, but in size-constrained environments it requires care.
Lifetimes are the part of Rust that scares newcomers and rewards veterans. Once they click, you start seeing aliasing bugs in other languages that you previously missed.
Macros in Rust are powerful but should be used sparingly. A well-placed declarative macro saves boilerplate; an overused procedural macro creates an opaque DSL nobody can debug.
Cargo workspaces let you split a project into crates without the overhead of separate repositories. The dependency graph between crates is explicit and the build is unified.
Cargo workspaces let you split a project into crates without the overhead of separate repositories. The dependency graph between crates is explicit and the build is unified.
Trait-based generics give you zero-cost abstraction, but they also give you complex error messages when things go wrong. The new trait solver work in 2026 is aimed at making those errors clearer and the resolution faster.
Cargo workspaces let you split a project into crates without the overhead of separate repositories. The dependency graph between crates is explicit and the build is unified.
Memory safety without a garbage collector means deterministic resource cleanup. Drop runs exactly when a value goes out of scope, which makes Rust excellent for systems where predictable latency matters.
Error handling via Result and Option is verbose but honest. Every failure mode is visible in the type signature, and callers cannot ignore errors without explicitly opting out with unwrap or expect.
Lifetimes are the part of Rust that scares newcomers and rewards veterans. Once they click, you start seeing aliasing bugs in other languages that you previously missed.
Cargo is the secret weapon. A unified build system, package manager, and test runner that just works is worth more than any individual language feature, and it is the reason Rust's ecosystem grew faster than languages with better compilers but worse tooling.
Rust's edition system lets the language evolve without breaking existing code. Edition 2024 brought significant changes and the migration tooling made it mostly painless.
Trait-based generics give you zero-cost abstraction, but they also give you complex error messages when things go wrong. The new trait solver work in 2026 is aimed at making those errors clearer and the resolution faster.
Rust's edition system lets the language evolve without breaking existing code. Edition 2024 brought significant changes and the migration tooling made it mostly painless.
Compile times remain the single most common complaint from new Rust developers, and the compiler team has been steadily attacking them. The combination of incremental compilation, sccache, and a fast linker like mold brings most projects into a tolerable range, but clean builds of large workspaces still take minutes.
Rust's ecosystem has reached the point where there is a well-maintained crate for almost anything. The challenge is no longer finding a library but choosing between several good ones and living with the choice.
Cargo is the secret weapon. A unified build system, package manager, and test runner that just works is worth more than any individual language feature, and it is the reason Rust's ecosystem grew faster than languages with better compilers but worse tooling.
Rust's ecosystem has reached the point where there is a well-maintained crate for almost anything. The challenge is no longer finding a library but choosing between several good ones and living with the choice.
The standard library is deliberately small. Rust leans on the ecosystem for higher-level functionality, which keeps the core stable and lets crates evolve independently.
The borrow checker is not your enemy. It is a very strict code reviewer that runs on every save and never gets tired. Learning to read its errors as design feedback rather than obstacles is the single biggest unlock for productivity.
Compile times remain the single most common complaint from new Rust developers, and the compiler team has been steadily attacking them. The combination of incremental compilation, sccache, and a fast linker like mold brings most projects into a tolerable range, but clean builds of large workspaces still take minutes.
Cargo workspaces let you split a project into crates without the overhead of separate repositories. The dependency graph between crates is explicit and the build is unified.
Error handling via Result and Option is verbose but honest. Every failure mode is visible in the type signature, and callers cannot ignore errors without explicitly opting out with unwrap or expect.
Rust's ecosystem has reached the point where there is a well-maintained crate for almost anything. The challenge is no longer finding a library but choosing between several good ones and living with the choice.
Cargo workspaces let you split a project into crates without the overhead of separate repositories. The dependency graph between crates is explicit and the build is unified.
Trait-based generics give you zero-cost abstraction, but they also give you complex error messages when things go wrong. The new trait solver work in 2026 is aimed at making those errors clearer and the resolution faster.
Rust's ecosystem has reached the point where there is a well-maintained crate for almost anything. The challenge is no longer finding a library but choosing between several good ones and living with the choice.
The borrow checker is not your enemy. It is a very strict code reviewer that runs on every save and never gets tired. Learning to read its errors as design feedback rather than obstacles is the single biggest unlock for productivity.
Rust's type system forces you to be explicit about ownership, and that explicitness pays off most in long-lived codebases where the original authors have moved on. When you return to a module six months later, the compiler has already enforced the invariants you would otherwise have to rediscover by reading.
Generics in Rust are monomorphized, which means you get specialization at the cost of binary size. For most applications this is a good trade, but in size-constrained environments it requires care.
Macros in Rust are powerful but should be used sparingly. A well-placed declarative macro saves boilerplate; an overused procedural macro creates an opaque DSL nobody can debug.
Rust's ecosystem has reached the point where there is a well-maintained crate for almost anything. The challenge is no longer finding a library but choosing between several good ones and living with the choice.
Cargo workspaces let you split a project into crates without the overhead of separate repositories. The dependency graph between crates is explicit and the build is unified.
Cargo is the secret weapon. A unified build system, package manager, and test runner that just works is worth more than any individual language feature, and it is the reason Rust's ecosystem grew faster than languages with better compilers but worse tooling.
The borrow checker is not your enemy. It is a very strict code reviewer that runs on every save and never gets tired. Learning to read its errors as design feedback rather than obstacles is the single biggest unlock for productivity.
The borrow checker is not your enemy. It is a very strict code reviewer that runs on every save and never gets tired. Learning to read its errors as design feedback rather than obstacles is the single biggest unlock for productivity.
Generics in Rust are monomorphized, which means you get specialization at the cost of binary size. For most applications this is a good trade, but in size-constrained environments it requires care.
Error handling via Result and Option is verbose but honest. Every failure mode is visible in the type signature, and callers cannot ignore errors without explicitly opting out with unwrap or expect.
Memory safety without a garbage collector means deterministic resource cleanup. Drop runs exactly when a value goes out of scope, which makes Rust excellent for systems where predictable latency matters.
The standard library is deliberately small. Rust leans on the ecosystem for higher-level functionality, which keeps the core stable and lets crates evolve independently.
Cargo is the secret weapon. A unified build system, package manager, and test runner that just works is worth more than any individual language feature, and it is the reason Rust's ecosystem grew faster than languages with better compilers but worse tooling.
The borrow checker is not your enemy. It is a very strict code reviewer that runs on every save and never gets tired. Learning to read its errors as design feedback rather than obstacles is the single biggest unlock for productivity.