WGTniv: My recommendation for all Firefox/Opera users is to manually set your cache size to at least 200MB in size.
OK, I've just done this in Opera and will try to play a round in it. It's not that it hasn't worked before, but play in Chrome has been smoother for me. As to browsing WGT pages and forums, I only use Opera for that, because its speed for text-based webpages seems unrivaled to me.
One thing that has never worked properly in Opera is navigation on the WGT ProShop homepage. ProShop pages do get displayed properly, but you can't choose, say, Clubs >> Wedges in the ProShop homepage menu. Because of this, I always need to launch Chrome if I want to take a look at something in the ProShop. It's a hassle, and I'm pretty sure the lack of functionality is not Opera's fault, because they pride themselves on being as standards-compliant as can be.
YankeeJim: I have the options set up to clear the cache every time the browser closes.
Wow, but you shouldn't do that, should you? That means you may have to re-download game components every single time you re-start your browser. I think WGT have frequently and expressly warned users against clearing their caches too frequently. I guess that applies both to the Flash cache & regular browser cache.
Infinito3010: Only window open when I play golf is WGT only.
Unless you mean the game window itself, that is not to be recommended either. Whenever someone complains of meter skips, my first advice to them is: close all other browser windows, especially WGT windows. If you keep the main WGT browser window open in the background as you play the game, you may experience increased meter skips. This is because your Friends list gets continually updated in the background, Flash advertisements flicker, skip, or may get reloaded, and lots of other shenanigans. My definite advice to everyone: close ALL other windows except the game popup window, whenever you play this game.
(Keeping a different browser, with non-WGT pages, open should be fine, though. Whenever I play the game in Chrome, Opera and Firefox are open on my computer as well, and there is no interference. But they are merely open; I don't really browse in them as I play the game, because that might have undesirable effects.)