Firefox? Safari? Internet Explorer? Which one cuts the mustard as far as you are concerned? If you are a regular browser, it is one thing. If you are developing an app, it is a different story altogether.
You have to ensure that what runs in one browser runs in the other as well. Fortunately, there are tools and applications for comparing the performance of the different browsers that are currently available. And the aptly-named Browserscope is one such resource.
Essentially, it will empower you to test the performance of all major browsers in the market side to side. A plethora of aspects are actually weighed up, and these are actually grouped under the corresponding tabs. It is worth naming them one by one: “Network”, “Acid3”, “Selectors API” and “Rich Text”.
I am not a programmer, and there is a good reason for that. While I don’t think a site like this one could make a programmer out of me, I do believe that those who are already conversant in such a field will put it to good use. If that description could be applied to you, maybe paying the site a visit might equip you with some valuable resources for understanding the way browsers function and how to adapt to them.