It is always a really big pain for me, as the longer I have Chrome open, the slower the Omnibox becomes, such that it will take half a second for it to register my keystroke.
Everything else runs extremely smooth. I can watch 2 HD YouTube videos and have 30 tabs open and browse with no lag at all.
What I have been doing so far is simply closing and starting up Chrome again, which fixes the slow omnibox until it starts slowing down again. I've noticed that even if I only have one tab open, this will still happen.