Both of these tips come from the "Obvious Department", but as I recently discovered myself not using them, I'm going to assume I'm not the only one a bit slow on the uptake.
First - it kept bugging me that Find within a file would only search forwards. I'd forget - cuss when it didn't find something I knew was there - and then either click the search backwards checkbox or quickly jump to line one and repeat the search. But - there is a better option - Wrap Search:
What's nice is that this seems to persist. Check it and you shouldn't have to check it again.
Now for the second tip. I work with a very repository of code. While searching, if I have to search from the root, it would take about 5 minutes or so depending on how loose my filter was. Turns out I had enabled regex for my search even when I wasn't using regex:
See the checkbox to the right? I had it checked and thought - ok - I don't need it - is it faster turned off? Turns out - it was way faster.
Hope this helps!