Comment # 11 on bug 1185267 from Gregory Baudet

I now udpated to Firefox 91.2.0esr as this update was released on Leap 15.3.
I got again the same problem as before, with firefox freezing.
I disabled DRI in Xorg config with Option "DRI" "False".
Then I was able to boot firefox, I changed the parameter to disable Hardware
acceleration in Firefox ( uncheck "Use hardware acceleration when available") 

After this, whether I re-enable DRI in Xorg or not, firefox works fine.

In my case, the problem seems to be related to Rocket lake desktop CPU and
intel graphics not very well supported in default Kernel 5.3 of Leap 15.3. I
have other issues with graphics hardware acceleration too like when launching
0AD game.

Enabling DRI "3" doesn't solve the problem in my case. I think it was enabled
by default anyway.