720p video laggy on a 1080p screen (please help)

Hey guys,

I have a Macbook connected to a 23.5 inch external LED monitor with a native resolution of 1080p. When I watch youtube/flash videos in 720p, the lag is unbearable. But if I watch a 1080p video it looks great. I've looked around and I can't seem to find a solution to this problem.

Thanks in advance.

Note: When a youtube video is uploaded in 1080p, I can view it in 720 with no lag. I've also messed around with my display settings and there seems to be no lag if I lower the resolution of my external monitor, but I'd like to keep it in 1080p if possible.

Cliffs: - 720p flash video lags on 1080p monitor WAT DO?

bumpity bump

You might want to ask in PC Hardware discussion, it's much more populated.