Enable Link-Time Optimization (LTO)

[zamazan4ik]

Hi!

I noticed that in the Cargo.toml file Link-Time Optimization (LTO) for the project is not enabled. I suggest switching it on since it will reduce the binary size (always a good thing to have) and will likely improve the application's performance a bit. If you want to read a bit more about LTO, I can recommend starting from this Rustc documentation.

I suggest enabling LTO only for the Release builds so as not to sacrifice the developers' experience while working on the project since LTO consumes an additional amount of time to finish the compilation routine. If you think that a regular Release build should not be affected by such a change as well, then I suggest adding an additional dist or release-lto profile where in addition to regular release optimizations LTO will also be added. Such a change simplifies life for maintainers and others interested in the project persons who want to build the most performant version of the application. Using ThinLTO should also help to reduce the build-time overhead with LTO. If we enable it on the Cargo profile level, users, who install the application with cargo install will get the LTO-optimized version "automatically". E.g., check cargo-outdated Release profile.

Basically, it can be enabled with the following lines:

[profile.release]
lto = true

I have made quick tests (Fedora 41, Rustc 1.83) by adding lto = true to the Release profile. The binary size reduction is the following:

• compiler: from 2.3 Mib to 2 Mib
• libwasm.so: from 385 Kib to 345 Kib

Thank you.