Scrabble now uses Adobe Flash, so the first thing to test is that you have the latest version of that installed. You can download the latest version from the official Adobe site here: http://helpx.adobe.com/flash-player.html
Secondly try clearing your flash player cache, see this post on the Adobe flash forum:
http://forums.adobe.com/message/4278569
Flash uses a lot of resources and there's a lot of animation in the game. It may help if you increase the storage available to Flash for pogo.com. Please see this article from the official Adobe website: http://www.macromedia.com/support/documentation/en/flashplayer/help/settings_manager07.html
After all this, please restart your computer and see if the games now run more smoothly.
Also make sure there aren’t any other processes running in the background (file downloading, playing music) which could be diverting resources.
Do your other games play smoothly?
Hope this helps.
