That's easy, go to Edit->Preferences->Advanced click Open Option Inspector remember the existence of the references (which you on the other hand dislike) CodeAssistOptions find the CodeAssistOptions and give the FloatingElementDelay a ridiculous high value

Please, don't forget to push the Apply button afterwards.

Still, if you type in something which might evolve itself into the head of a built-in symbol, an educated guess appears, but the circled i has gone.

I finally decided to correct my comment above because it does not work. It does not work either when AutoPopEnable and FloatingElementDelay is set false... Will you PLEASE give us a choice to disable all these popups in the next version of Mathematica?

Also, when clicking at some special position on the heads of expressions, they are selected entirely, which is very annoying too. I went back to version 9 because of all this, which is a pity because otherwise I like version 10 a lot.