As luck would have it, this extension popped up in my RSS reader tonight. Seems to work as advertised for me -- fetching of the URL bar suggestions and searching of history items is noticeably faster.

I also happened upon this little tip earlier in the week. For keyword search bookmarks, you can use some simple javascript to go to different URLs depending on whether you supply a keyword or not. e.g. for Wikipedia, I have keyword "wp" set to:

javascript:if('%s')%20location.href='http://en.wikipedia.org/wiki/Special:Search?search=%s';else%20location.href='http://en.wikipedia.org/wiki/Main_Page';

So, if I just type "wp" I go to the main wikipedia page, but if I supply a keyword, it searches for it. Soemthing I always thought would be nice but didn't realize was possible until now.