Phoronix reported that the Meta (Facebook) BOLT post-link optimizer is giving them approximately five percent performance gains in the Linux kernel.
There is now a public guide for carrying out a BOLT-optimized Linux kernel build and roughly 5% better system performance to expect from such an optimized kernel.
One important thing to keep in mind is that, with the same workload, a performance gain should decrease power usage: completing the same work with less CPU time.
The comments for this article also mention CachyOS as a performance-by-default Linux distribution. While CachyOS appears to be focused on game performance, they list some of their performance optimizations which might be a useful guide to performance tuning on Linux.