As peke said in comment #30: It's fixed in Firefox 19 (thanks!) but it can still happen when using hardware acceleration.
I turned on layers.acceleration.force-enabled today (Firefox 20 / Ubuntu 12.10 64-bit / nvidia 310.14) and started noticing the issue again.
I can see it clearly in gmail, and the strange thing is, that it's temporary: font hinting is strange when scrolling, and after you stop, in 2-3 seconds it jumps to being ok. I'm now attempting to record a screencast to show this.
As peke said in comment #30: It's fixed in Firefox 19 (thanks!) but it can still happen when using hardware acceleration.
I turned on layers. acceleration. force-enabled today (Firefox 20 / Ubuntu 12.10 64-bit / nvidia 310.14) and started noticing the issue again.
I can see it clearly in gmail, and the strange thing is, that it's temporary: font hinting is strange when scrolling, and after you stop, in 2-3 seconds it jumps to being ok. I'm now attempting to record a screencast to show this.