Improve compile times

(edited by @emilk)

Improve build times, and aspire to reduce number of dependencies and code bloat in the process.

Some useful tools include:

• cargo clean && cargo build --timings -p rerun
• cargo tree
• cargo machete
• https://github.com/google/bloaty
• https://github.com/RazrFalcon/cargo-bloat
• https://github.com/dtolnay/cargo-llvm-lines
• cargo udeps to find unused dependencies

See also:

• https://fasterthanli.me/articles/why-is-my-rust-build-so-slow

Reducing dependencies

Some ideas:

• replace clap with something simpler, like pico-args
• replace sha2 with a simpler hash
• replace chrono with time
• replace image crate with https://github.com/etemesi254/zune-image
• re_web_server should be able to use something must simpler than hyper+tokio
• replace lazy_static with once_cell ?
• remove strum
• enumset can be replaced with something simpler (maybe by macro_rules!)
• reduce naga features?
• crossbeam (std::sync::mpsc is now using the same implementation) - though crossbeam compiles in 2s, so probably not worth it

Done:

• https://github.com/rerun-io/rerun/pull/1425
• https://github.com/rerun-io/rerun/pull/1407
• https://github.com/rerun-io/rerun/pull/1406

Other tasks

• #347
• Track build time and number of dependencies over time like we do for benchmarks
• Add cargo-deny to the CI of other crates, like arboard, to prevent duplicate dependencies of e.g. nix
• In puffin, add support for lz4_flex: https://github.com/EmbarkStudios/puffin/pull/130#issuecomment-1495641210

Other

We have some instructions for improving build times in https://github.com/rerun-io/rerun/blob/main/BUILD.md#improving-compile-times