Are you sure that is it? I'm using a Radeon HD5770 and my frames also drop when there are many players on screen at the same time. I think it's a CPU issue, I'm using an old Athlon 4400 x2 in my system and it seems that the bottleneck lies there. As usual it's a combination of both. And a 4400 X2 is kinda old yes and relatively slow.