i am asuming, that you are talking about the allocated disk cache.
Some people who makes projects with huge settings( 100 3D layers offset in z space.. ect.) are very sensetive about deleting cache, as it’s a lot of wasted work time re rendering, the entire scene.
Though if you are like me, who only makes 10-20 sec tv adverts, and dont really do any major projects.
I.e Re rendering your scene wont be too big of a deal.
you want the fastest drive you can get.
you “flush” (delete the all the cache files) by going to the “Media & disk cache” menu in prefrences.
And then clicking “empty disk cache”
hope it helps 🙂