TLDR for people who didn't read: The speed difference came from the allocator. Rust switched from jemalloc to the system allocator per ticket #36963[0] for va

TLDR for people who didn't read: The speed difference came from the allocator. Rust switched from jemalloc to the system allocator per ticket #36963[0] for various reasons (like binary bloat, valgrind incompatibility, etc...). Go uses a custom allocator[1] instead. To make 'Rust Go fast' (pun intended), one can use the '#[global_allocator]' to use a custom allocator (in this case, with the jemallocator crate) to make allocations fast again. [0]: https://github.com/rust-lang/rust/issues/36963 https://github.com/rust-lang/rust/issues/36963 [1]: https://golang.org/src/runtime/malloc.go https://golang.org/src/runtime/malloc.go