Following some guidelines of the Rust Performance Book here are some things we can try to improve performance:

• Add codegen-units = 1 to release build
• Use a faster allocator. E.g. mimalloc works on all operating systems

Not so easy:

• properly profile to identify hot parts
• remove clones/allocations where not needed
• use profile-guided optimization (e.g. via cargo-pgo)
  • unfortunately this is currently not working with LTO and the PGO version is 10-20% slower than LTO
  • might be available in the future in maturin directly, see here

Quick tests with codegen-units = 1 added to release-lto (see here) show performance improvements of benchmarks of up to 12% (mean is about 7%) while for dual_number, changes are a bit smaller (see below).

Proper benchmarks (across all benchmarks) with comparison to current release workflow are needed but this might be an easy-to-get improvement if it turns out to be faster for all cases.

• Benchmark: dual_numbers
• System: methane/CO2
• main: main branch + lto
• main_codegen: main branch + lto + codegen-units = 1
• develop_: like main

Execution times in µs

Slowdown t_f64/t_d for each branch/option

Relative difference in % w.r.t. main + lto for each dual number (t_d_branch - t_d_main) / t_d_main * 100