Fill the additional points in the api_perf_hacks

Currently I explained caching point here https://github.com/InsidersEdge/Fairly-Decoded/blob/main/api_perfs_hacks/index.md . Feel free to extend the the other points that are left empty

Start with api_perfs_hacks/index.md and read the existing caching section. Identify the other points that are currently empty, then document those points consistently with the caching explanation. The work is done when the remaining listed points have useful explanations and the Markdown remains readable.

Written by the indexing model from the issue text.