Hm, which version are you talking about? This new, with pixman, or the previous one? With the new one I don't see any slowness and even less in the menu.

NB! One thing I haven't mentioned anywhere is that there are 2 version of Fennec - with QT and GTK GUIs. QT is faster but is less adapted for Maemo and has some bugs with virtual keyboard support and buttons and text fields placement on some pages. Also GTK Fennec can be used in Portrait mode. I'm releasing only those QT builds but I have built many GTK ones too. I just built GTK with that pixman library, gonna test it and see how it is, then probably upload it.

P.S.: Edited the first post.
I forgot to mention that I took into account Raimu's request to stick to Fennec and not Firefox branding(Icon and labels)

P.S. 2: As I thought GTK build is again a crawling snail, absolute trash...