To reproduce first go to a forum thread such as this one in firefox:
click the page numbers 1 2 3 4 etc and watch the navbar. In firefox it's solid, doesn't blink. In other browsers sometimes the navbar blinks or the page in general flashes. There are times when I've gotten it to blink 10 times in a row in browsers other than firefox. I notice in chrome the navbar is static but colors in the navbar shift when moving between various pages instead of blinking.
I'm on a recent macbookpro retina, latest OSX and latest browser builds. I am curious if others are seeing this? One of my developers spotted it while we were trying to figure out the issue on my site. Then trying it here it did the same. Maybe it only happens in OSX, I do not have a windows machine to test on. I have tested on 3 macs, same blinking.