The talk is about optimizing BPF hash maps and the speaker discusses benchmarking, different hash functions, and benchmarks of maps using old and new hash functions. They focus on the xxh3 hash function, which outperforms jhash for all key sizes, and propose using jhash2 for key sizes that are divisible by 4. They also mention that xxh3 performs much better with O3 optimization compared to jhash and xxh64. The speaker suggests that using xxh3 is a good candidate for stack trace maps and possibly for hash maps as well. They mention links for benchmarks and papers used. One audience member asks about only compiling the hash map file with O3 instead of the entire kernel, and the speaker confirms that this is possible.