I think that's unlikely. ST2 is already exceptionally fast and complete as an editor. As an IDE, ST2 requires plugins. These plugins are written in Python (which can use libs written in C) as opposed to vimscript or elisp. Moreover, these plugins aren't required for editing text files (or having SublimeClang isn't going to significantly slow down editing python files).

Vim and Emacs kill that argument. Neither is slow, and both are older than dirt in computer years. Sublime Text may continue the march without becoming super slow as well. I'm sure a Java-focused IDE could be fast and excellent, but that's not their focus.

I'm only using ST2 because TM2 took forever to release and even the the alpha wasn't compelling.

So I'm much more worried about developer fatigue than bloat in my editor choice.