I've implemented the file caching for now. Being that I have a lot more browsing visitors than editors, I think that should make a noticeable difference. I'm going to keep an eye on the situation and see if that makes a dent. If not I'll have to look into the other solutions and see which I could carry out in the shared host environment. Shell access is available but costs a little extra, and the list of functions disabled are located here http://wiki.lunarpages.com/Disabled_JailShell_Commands
FYI, the extensions I'm using are Cite (Version r47190) , ParserFunctions (Version 1.1.1), ConfirmEdit (Version r36959) w/ FancyCaptcha.
Thanks for all the suggestions so far, I've learned a lot.