I recommend consuming everything Brendan Gregg produces. His work is mostly around kernel performance profiling and tracing, but you can learn a lot from just doing that. Also, the vast majority of time when you need to dive into kernel internals it is for performance reasons.

https://www.brendangregg.com/linuxperf.html

If you prefer physical books “Systems Performance” by Brendan is good as well.

As the sister comment says, Linux Programming Interface is really good for learning linux system programming topics but it is mostly focused on user space.

For more userspace stuff I like Chris Wellons‘ blog at nullprogram.com