Then what do you need a cache for in the first place? It's not recommended to let 3rd party software mess with the Firefox profile. Firefox has a built-in mechanism to clean it's cache. Use that if you cannot resist cleaning it.

As for the 2500+ files, that's part of the file structure how Firefox maintains cached items. Leave it alone. If you deliberately destroy that file structure, Firefox will need to rebuild it every time upon starting up. I doubt that will help to reduce start-up time.

Type about:preferences#privacy<enter> in the address bar. The button next to History, select Use Custom Settings.

At the bottom of the page, turn on Clear History When Firefox Closes. At the far right, press the Settings button. Turn on ONLY Cache and Form And Search History leaving the others off.