First, I was using MicroB since I got n900, after 1,5 year I tried Firefox. Both of them are slow in my opinion in comparison with Opera Mobile. Im writing this using Opera having 5 tabs opened. However it does not support flash at all...Scrolling is smooh too. In MicroB I often had to wait for window refresh, before I was able to scroll page down (Im talking about this anoing canvas with hatches)