The whole point of vim is normal mode, not insert mode. Insert mode is just typing, but normal mode is code or file navigation. Its not about typing speed but deliberate action and precision - with vim you need only a couple of keystrokes. In this context speed refers not to typing code but to doing what you mentioned quicker (at least for code search, jump to definition, go back in cursor history) but there is vimium for the web which helps with research. My hands are slowly failing me and vim is a god send.

I think that in order to not break your flow, you should be able to translate your thoughts (the answer you found) to code or text as fast as possible. Typing slowly when you know what you want to write can be frustrating for one (lowering your motivation), but most importantly is too trivial a task to prevent you from thinking at the same time (and thus parasitic thoughts can break your flow). A HCI that can help you write your code as you think of it (and maybe log the thought process for future reference !) would be awesome on that front.