Richard Startin writes in depth about Java performance, profiling, vectorization, sampling algorithms and low-level CPU effects.
HN commenters recommend it as a deep dive, praising posts on 4K aliasing and reservoir sampling as well written and well illustrated.
Vanilla Java is a great resource. The work that Chronicle does got me into low latency Java as well (not doing java now though).
Some other great resources I used:
* http://psy-lob-saw.blogspot.com/ - Not updated since 2018, but still great stuff in there
* https://richardstartin.github.io/ - A few posts per year. Richard does a lot of interesting things.
This is a really nicely written and illustrated post.
An advanced extension to this is that there are algorithms which calculate the number of records to skip rather than doing a trial per record. This has a good write-up of them: https://richardstartin.github.io/posts/reservoir-sampling
For those interested in a deeper dive, Richard Startin had a nice post on the topic https://richardstartin.github.io/posts/4k-aliasing
https://richardstartin.github.io/posts/reservoir-sampling#background-faster-methods-for-random-sampling