Slow jQuery fadeIn and fadeOut

I'm using jQuery fade effects for my "random fact" section near the top of the page on www.funfactz.com. I've tried in Chrome, IE, and Firefox. Does it happen for everyone else?
It used to be smooth and work fine, but now it seems to be lagging so much that it appears as a delayed show/hide without any animation.
What can cause this? I'm not sure what change to the website may have caused it as I've only just noticed it and have made many changes over the…
Slow jQuery fadeIn and fadeOut

See original post by Galaxian