Is this the first time font rendering has not worked well with hardware acceleration enabled? It might be a regression in the latest nightly that will be remedied, or it might be a change that would be hard to undo. I'm not sure of the best way to determine that. If it doesn't clear up in a few days, you could file a bug indicating which nightly started the problem.

ok, ty for answer. waiting for fix )

Note that the gfx.content.azure.enabled pref no longer has effect and you can try to disable Direct2D by setting the gfx.direct2d.disabled pref to true on the about:config page and leave hardware acceleration otherwise enabled.

See also comment 414 in bug 812695:

• https://bugzilla.mozilla.org/show_bug.cgi?id=812695#c414

That way you still have the benefit from hardware acceleration, but may not suffer from rendering issues.