Firefox window distortion when moved between external and retina display

Two issues with firefox browser that I haven't ran into before.

rMBP mid 2012 with external HDMI 27" ACER LCD

1. When moving (not scrolling within) Firefox window between my retina laptop display and the external monitor the Firefox windows distorts the graphics very briefly once I release the magic mouse or track pad. If I use the tool Spectacle to move the window to the external display, no distortion. The problem is very noticeable and I am puzzled as to why I haven't found any other forum. It has persisted for as long as I can remember. I had the laptop in at the Apple store and it passed the video test so it isn't the faulty GPU issue. It is using nvidia GT 650m.

2. I can't type text into this support forum in the firefox browser. It just doesn't do anything until I type really really fast, then it starts displaying. Weirdness. I used Safari without any issues.

I just want to know if these are known issues or not because my google search and forum search above didn't turn up anything.

Thank you.