I've found double-tap zooming works a little better in Firefox than MicroB and use it most of the time to zoom. You can also zoom Firefox with Ctrl+up-down buttons. And zooming with the volume control is either in the nightly test builds already or will be soon. Expect volume zoom, more features plus more speed in the next official release.

I just don't get where everyone keeps saying Firefox is slower than MIcroB. It does start up slower because it doesn't pre-load into memory at boot like MicroB, but loads webpages just as fast when I compare the two. Firefox has a newer rendering engine, runs javascript as fast or faster than MicroB and handles some complicated websites I have to access for work better than MicroB. Am I missing something here?

The only real problem I have with Firefox is it doesn't yet let me organize bookmarks in folders.