If you have a 64-bit system, you may want to try out the Firefox-based browser Waterfox which is optimized specifically for 64-bit systems.
I haven't tried it myself and am sticking to Pale Moon since I have a 32-bit system, but you folks out there that have a 64-bit system may want to try it out. I keep reading great reviews about it. Some people claim it's 20%+ faster than the official Firefox.
If you download it, be sure to download and install 64-bit versions of Flash Player, Java, and Silverlight.