Random loss of framerate

I'm running x4 clients and I get about 70 FPS on my main screen. Sometimes I will get a drop of 30-40 FPS and it stays there. When I bring up my task manager my FPS magically returns to 70 FPS. What could be causing this?

[Alge]

Without more details it is hard to say. One possibility is that your GPU is being throttled or you are hitting some sort of system bottleneck. I'd suggest monitoring your system using Open Hardware Monitor - see here for a link.