Hello jimmassie,
this problem is sadly quite common at WGT. There can be several reasons for this "mistake". On the one hand, it can be a problem that is caused solely by your computer/settings. For example, that is the case when your computer gets seriously slowed down by random malware or (the better case for you) saves all new webpages you visit and settings you configure in the cache without deleting former settings. That can cause confusions in the way your computer processes this flash game. This part of the problem can only be solved by you, by checking your computer with a good antivir program, activating a firewall if you haven't done that yet and (i know nobody likes this sentence) clear your cache / temporary internet files / saved webpage trend.
On the other hand, flash is a pretty good keyword. The problem is normally caused by a combination of one of the following two things and uncleared cache files.
1) Your browser got updated and something in the implementation / processing of the flash engine got changed.
2) Adobe Flash Player itself got updated and changed some characteristics.
In case two, the same step as the final one of the first passage should solve your problem. In case one, redo the current browser update and restart your computer. If the problem still occurs, you might want to use a different browser (possibly Internet Explorer, Mozilla Firefox, Google Chrome, etc...) and see whether your game performance gets better by that (as proposed by SingingRoofer too, thanks for that).
If you have any questions about the above steps, please feel free to write them down in this thread or send me a private message.
Cheers, Hans