Reviewing and testing Bitcoin Core pull request https://github.com/bitcoin/bitcoin/pull/25325 "Add pool based memory resource" by Martin Leitner-Ankerl.

It's a fundamental low-level algorithm change with the goal to cache more coins with the same memory usage and to allocate and de-allocate faster. The performance improvements are impressive.

It's not easy to review and ensure that the change causes no issues. Nevertheless, I think this kind of work is important to make Bitcoin more decentralized and robust.