I got a question, do you have wi-fi or cable connection?
If wi-fi, try using cable connection and see if it makes any difference.
Btw, your computer is fast enough to run Flash games just fine. I'm quite sure other flash games won't "lag" as much or at all if you play those.
Though, there is also a possibility that you can't do nothing from your end. My 1st reply in THIS
topic explains what i mean.
You could also try and play via direct link to see if it helps.
I use v2.2J at Funny-Games.biz direct link
Or you can try the v2.5B from official site direct link