Need some help

Hey guys i'm new to isboxer and i have a question..i was using 3 chars and everything was working just fine and yesterday i bought 1more account and with 4 accounts my FPS drop down from 60 to 25-30fps and is moving bad..
Pc specs : i7 processor..16gb ram..video : nvidia gtx 560..my pc is good enough i guess for 4d3 clients..can i fix it? any advices?

[MiRai]

It could easily be that your GTX 560 isn't up to the task of rendering out four D3 clients at your current settings or FPS. Drop your settings or lock your FPS at a lower number across your game clients.

You can also check this - http://isboxer.com/wiki/HOWTO:Tweak_your_framerate