Try Mozilla
Aurora (its FF 6.0
alpha)
I find it is definitely faster than FF 5, which is already pretty fast. PDF isn't too much of a turn off since almost everybody has Adobe PDF Viewer installed anyways.
@kn19h7
What memory issues? I have left firefox (6.0) running continuously for over 24 hours and at most it has used ~400mb from what I see in Task Manager. If it really is a concern to you, you can see this:
http://kb.mozillazine.org/Reducing_memory_usage_%28Firefox%29
or if you really need to, you can tweak the FF config (not recommended unless you know what you are doing)