Had a quick google search and Found that Firefox is the fastest. I personally recommend firefox too, because I am its active user.
Else, You should try Chrome, Its awesome too, but a little more resource consuming.
And finally, I don't think there is any reason to recommend opera, Because it is built on chrome, and will provide you same speed as chrome, and will consume same resources as chrome do, and It lacks a number of addons that I need. So, I wouldn't recommend you Opera.
At strong computers, means to those who have a lot of RAM and processor is powerful does not matter what it is used, but on older computers with low power processors and with little RAM Chrome and Mozilla are too slow, my recommendation is the older version of the opera, means versions 12:16 and lower