Evaluate Profile-Guided Optimization (PGO)

Hi!

There is an idea that PGO could help with improving performance even more! 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 PostgreSQL and ClickHouse.

There are several options. I'd appreciate it if you could provide an easy way to build Qdrant with PGO. And experienced users will be able to do it on their own for their own usage scenarios. Another option is to optimize Qdrant 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. Another idea of how to use PGO - optimize your own cloud-based Qdrant installation.

As an additional optimization way, I suggest taking a look at LLVM BOLT. But from my experience, it would be better to start with PGO and then try to use BOLT.

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

Start by reviewing the PGO proposal and the recommended cargo-pgo approach for Rust projects, then compare it with the alternative LLVM BOLT path. Determine whether Qdrant should expose an easy PGO build workflow, use a generic profile, or provide optimized binaries. Done means documenting and validating a concrete approach, with any profile-generation requirements made clear.