Several speed benchmarks have been done by other websites. Currently, latest Safari, Opera 9.5 and Firefox 3.0 are pretty much equivalent (faster here, slower there) - depends on context, but they are all generally 2-5 times faster than IE 7, with still better standards support. So, what's left to compare them with?
- with its mobile orientation, Opera's cloud platform was a no-brainer feature. It really was logical for Opera to add this, and to host it. It also has a small enough user base to host the cloud, and is "fixed-function" enough (ie. you can't really extend Opera) to remain stable.
- with its toolbox working mode, Firefox needed to get faster everywhere: it's pretty much a platform using XUL, CSS and Javascript to write applications with, allowing websites to make use of the whole browser to provide applications to the user; the off-line mode, although discrete, is there; enjoy off-line Google Apps right now! Please note: storing session settings in the cloud was already available in Firefox 2, through several extensions.
- its integration with Apple systems makes Safari the ideal iTunes+Quicktime companion; if you have a Windows machine crawling with Apple apps, Safari is a good choice for UI consistency. However, chances are you'd already have a Mac.
Still, these browsers really are faster: loading Yahoo!Mail, Gmail or Hotmail on any of these browsers is now an order of magnitude faster than on IE. Firefox 3 got a great speed-up over 2 in this area (DOM-heavy, standards-compliant websites).
Mitch