CtrlP [1] with its fuzzy search is really a delightful way to move around projects with many files. If you have an extraordinary amount of files you can also add ag [2] in the mix [3] for faster searching/grepping.

[1]: https://github.com/ctrlpvim/ctrlp.vim

[2]: https://github.com/ggreer/the_silver_searcher

[3]: http://stackoverflow.com/questions/18285751/use-ag-in-ctrlp-...