Ctrl-p is great but I agree, lack of caching is a signigicant pain point. I raised an issue on that and the author explained it's because there's actually no mechanism for Vimscript to do it, so someone would probably need to come up with some way to spawn headless Vim from a periodic Cronjob. A standalone app like VimR can also route around this constraint.

https://github.com/kien/ctrlp.vim/issues/222