I usually follow installation instructions provided with the extension documentation. Often it's just a composer require command. Other times there are post installation steps like: di compile, setup:upgrade.
I have a pretty slim local development vm, which performs well normally, but for what ever reason, after installing some extensions it crawls[goes extremely slow, uses tons of resources] for a few hours. I imagine it has something to do with rebuilding caches? Is there anyway to speed this up, or at least make it more predictable / consistent? e.g. a cache warmer?
Just realized one of the extensions seems to have disabled cache. I believe that was the reason for the slowness. It was probably in a console message. Recommend more emphasis, impacts performance greatly.
There are many way to slow down the performance.
1. check server response
2. avoid third party extension
Check website in gtmetrix speed test tool and get what takes max time to load.