Honestly? I only have 2x1.3GHz, but it loads damn fast for files <= 5MB. How large are the files that you open that make your browser inresponsive?
I just get the spinning wheel effect, while the CPU usage scales all the way up, until the whole document is downloaded, processed and finally displayed.
With native readers, it is almost instantaneous.
https://drive.google.com/file/d/0B0Ne3vac3uJuOTB0Y2owLVN3MzQ