Evaluate Profile-Guided Optimization (PGO) and LLVM BOLT

Hi!

There are a lot of examples of different software, where PGO helps a lot with performance - you can check it here. E.g. in this list are a lot of databases like Redis, MongoDB, and PostgreSQL.

We need to check the PGO effects on SpacetimeDB, and if it works well - write a note in the SpacetimeDB documentation about PGO. I'd appreciate your providing an easy way to build SpacetimeDB with PGO. And experienced users will be able to do it on their own for their own usage scenarios. Another option is to optimize SpacetimeDB build with a generic-enough profile. Providing PGO-optimized binaries could be a trickier task (since it requires preparing a good-enough profile) but as an option would be great to see too. Also, you even could optimize distributed from the official sites binaries with PGO (if would be able to collect a generic-enough profile).

As an additional optimization, I suggest looking at LLVM BOLT. But from my experience, starting with PGO and then using BOLT would be better.

For the Rust projects, I recommend starting with cargo-pgo.

I understand that the project is still in the early development stages. So I think the issue is just an improvement idea for future developments.

No files, tests, or build entry points are named. Start by reviewing how SpacetimeDB's Rust build is currently performed, then evaluate cargo-pgo for representative workloads and consider LLVM BOLT afterward; done means reporting the PGO effect and documenting an easy build path if it is effective.