Probably not very well. Currently running 5760x1080 3 monitor on my GTX 770 4GB, on medium I average 40 fps, using 3 GB of vRam.
Most games I run at medium to high graphics and I average about 3 to 3.5GB of vRam, at 40 FPS, so I use adaptive Vsync, and get pretty smooth performance. My rig has no bottle necks, its a intel i5 3570k OC'ed to 4.1GHz, 8 GB of ddr 3 1600, dual channel, with a ssd.
I still get some studder and feel any less gpu and vram would make it unplayable.