Hi everyone, thanks for all the responses to this. Good to know for absolutely sure that it's not the card. Let's hope NVidia fix the drivers quickly! Thankfully the glitch isn't game-breaking but it is disappointing to see.
Cheeto- yes, I get frame-rate drops when in crowded areas like hunts and Odin, but I've come to expect this and it's far from unplayable, thankfully. Anything is better than the memory leaks I suffered with my previous (AMD) card, which caused the game to drop to less than 5FPS seemingly at random and then crash shortly afterwards!
We're wandering off-topic (although I think we've established what the problem is above) but since we're talking performance: I've been pondering a CPU upgrade recently and was wondering how much impact it might have on FFXIV, which some people have said is fairly CPU-intensive. Currently rocking an i5-2400 at 3.1GHz that I've had for the last few years; any value in upgrading? Or should I just wait for the DX11 client to see if performance improves? I'm far from unhappy with how FFXIV performs, but it would be lovely to have the FPS a little more consistent when out in the open world.