I'm having the same issues. Running 2 x 290X (Only one working in FFXIV ofc) on a 4k monitor. At first I thought the resolution was the problem but seems I was wrong.

As most have already posted porting out of any highpop place, or sometimes just moving around in a highpop area, fps drops to 1-2 and often than not game crashes a couple of seconds later.

Other times models don't show/load or random textures, most often the map and/or minimap background won't load, symbols and legends on the map is showing though.

Currently running Catalyst 14.7RC, unsure if I have had the issue on these but can't say for sure since I havn't played all that much FFXIV with these drivers. I know I have the issue with 14.4 (current stable) or older drivers though.