7
Easy version of is:
1) don't cache anything that changes alot!
2) cache any blocks you can, that don't change, in block menu also as well as in prefrences, if the module is static content.
3) fix all W3C errors, as if there are tons of errors this slows page loading time.
4)if you are on XOOPS 2.0.13.2 get the locical table checker (not sure if it works with newer versions)
use this to fix error in the database that may apper over time and in modules.
surprising some times what you find shows, like odd users not in groups, can slow your core down.
5) Clear uneed auto notifications in private msg you can have thousands if they don't select email after awhile.
6) Get optimise database module and use regularly.
I do all these and when I was on dial up I had no problems.
Other then the host moaning as my site got so many modules to be on shared hosting.
So I seperated my site into 2 yet I really do need my own server
