I have a twin screen setup, both being driven by a NVIDIA GeForce 8600 GTS. I have been flying using both screens to give one large wide screen. Because of overlay problems I've been running it in windowed mode. For some time this worked fine. However recently I found that frame rates were dropping to such a level that the sim was unusable. ( I was flying the Just Flight Constellation.)I was getting fractions of a frame per second. However, by accident, I came across a solution. By switching to full screen mode and then back to windowed mode everything suddenly became fine. I was getting good frame rates - at altitude sometimes up to 60fps.Obviously this solution works but I am curious to know if anyone has any idea as to why this happens?CheersMalcolm WrightMy computer is a Dell Vostro 400 with dual 2.66 CPU's. 6GB of main memory and two 500GB drives. I use XP Pro with SP3 installed. Two 22" monitors one Philips the other Dell.

No one really knows, because every system is different. There are so many variables that only experimenting will find the best results, for most.Some options that others have tried and for some they work, for others they dont.Using full screenUsing windowed modeUsing windowed mode and ensuring the task bar doesnt touch the window(or move it to second monitor)Locking frame ratesUnlocking frame ratesChanging video driversUsing Nhancer (Nvidia)Trying every tweak known to manusing a service like www.fs-gs.comThe list goes on and on

Hiding the taskbar in Windowed mode normally gives the same frame rates, providing the Task Bar IS hdden, as Full Screen. HTHM.

When in windowed mode moving the mouse cursor out of the FSX window can also nett you a few extra fps, especially in complicated vc's with lots of clickzones. Waiting for the cursor to disappear works as well...

I can also confirm that setting the taskbar to auto-hide fixes the frame rate difference issue in windowed mode. :)

Thanks to all that responded. I'll try the hiding task bar trick.CheersMalcolm

I didn't notice a frame rate change. The biggest advantage for me is no more BSOD when maximixing full screen after performing such essentail tasks as checking AVSIM. Took a while to get used to, but I like it now.