The firefox4-4.0-0.26.beta12 package install this new version besides the version 3.x. So you will have 2 entries in the Internet menu.

Start by reading :

As always :

yum remove firefox4
yum --enablerepo=remi install firefox4

If you prefer to replace the system firefox, you can also install firefox-4.0-0.26.beta12 from remi-test repository.

yum remove firefox firefox4
yum --enablerepo=remi,remi-test install firefox

This RPM use the Gecko engine provided by xulrunner2 (which could be installed beside the default system xulrunner).

The Add-on compatibility reporter 0.8 allow to enable extension which are not compatible for test.

Some benchmark results:

  V8
More is better		 SunSpider
 Less is better		 Kraken
 Less is better
Firefox 3.6.10 382 1 469.4 ms 61 796.7 ms
Firefox 3.6.13 394
 1 435.3 ms 60 490.3 ms
Firefox 4.0b7 4 010
 241.7 ms 5 278.1 ms
Firefox 4.0b8 4 634
 236.8 ms 5 221.3 ms
Firefox 4.0b9 5 158
 218.5 ms 5 143.7 ms
Firefox 4.0b10 5 099
 225.8 ms 4 712.3 ms
Firefox 4.0b11 5 050
 231.9 ms 4 734.2 ms
Firefox 4.0b12 5 090
 237.4 ms 4 548.8 ms

Tests run on:

Fedora release 14 (Laughlin)
Intel(R) Core(TM) i5 CPU 760 @ 2.80GHz