Making Rust faster than C

Rust, being a systems language, should be best in class for performance-critical software.

While the performance difference with C is small, it currently blocks Rust implementations from being widely adopted. Why go through challenging migration only to end up with a 1% performance drop or with +2% additional battery drain.

Our mission is to make critical infrastructure software safer. Performance considerations must be removed as a blocking counter-argument for adoption in performance-sensitive projects, where the impact is highest.

This initiative exists to contribute to change, to change Rust's performance story with the ultimate goal of making it faster than C.

What we've done

Our work on zlib-rs put us on the path to improving the performance of state machines. Complex state machines are niche but foundational to many programs, such as parsers, interpreters, and networking protocols.

Folkert de Vries wrote an RFC to improve code generation for state machines and bjorn3 implemented a proof of concept in the Rust compiler.

The proof is in the pudding: zlib-rs built using the PoC is 14% faster in a relevant benchmark.

We want to acknowledge the work done in the Zig ecosystem that inspired our proposal. We'd also like to extend gratitude to Tweede golf for supporting the initial effort.

What's next

The improvements of RFC 3720 are only relevant for specific programs, but it shows that there is room for improvement. While outperforming C by 5% might be unlikely, even a shift from -2% to +2% would significantly improve Rust's story and, more importantly, its impact.

The gap with C can be closed if we can better use Rust's advantages over C, i.e., having access to more information about how the compiler can optimize.

A significant coordinated effort is needed to reach the goal of making Rust faster than C. We are working on a plan and seeking funding to support this initiative. Have a look at our preliminary workplan or contact us via rustfasterthanc@trifectatech.org.

Meanwhile, we will continue to work on stabilizing the RFC as a first step in the right direction.

Making Rust faster than C