For anything pre-G3, I've found various versions of Netscape Navigator to be the fastest and most stable, and surprisingly the best at rendering pages well without CSS, Java and other fancy stuff. Classilla is best on G3 w/ 64Mb of RAM or more. Assuming you have a machine that meets those, Classilla will blow navigator out of the water, especially on features.

I've not tried Classilla on my 2300c, b/c atm, I'm stuck with 8.5. Classilla will technically work on 8.5, but I don't want to have my first experience with it on a lower spec'd machine be polluted by the oddball of os 8 line.