D2X-XL v1.14 has a new approach to frame rate capping by now offering nothing more than an option to have the frame rate sync'd with your monitor's vertical refresh signal (to avoid tearing). What D2X-XL actually does when this option is checked is to not cap the frame rate at all, allowing you to link the screen refresh to the hardware's v-sync signal via the OS's driver control panel. I have chosen this approach because the required driver functionality is rather hard to implement on other operating systems than MS Windows and that way the driver will be able to always handle this properly.

If this box is unchecked, the frame rate will be capped at 60 fps. This is a reasonably high setting at which no human being in the world can detect any stuttering any more. The human eye is only capable of distinguishing singleimages up to a speed of about 30 fps. The reason for this is that particularly the pigments in the eye's light sensitive cells required for color vision need about that time to refresh. The human eye is capable of detecting brightness changes (flickering) at a higher rate (up to 100 hertz), but that has nothing to do with perceiving a fast sequence of stillimages as fluid movement of the displayed scene. If you claim you can perceive stillimages at a framerate significantly above 30 fps, then you are a case for the Men In Black.

I know there are people who cannot be convinced with as many scientific research and proof as there could ever be that this is true. If you are one of these people don't even try to argue about that with me. If 60 fps is good enough for id Software games, it is certainly good enough for D2X-XL.

An explanation can't hurt.

Seeing your frame rate going to several hundred fps is good for nothing except maybe giving you warm fuzzy feelings for your hardware (if that is what you want, just check the "frame cap: v-sync" box). You don't need more power when you're already speeding down the highway at 250 mph. You need it when toiling uphill, and that's what v1.14's increased rendering power is good for: It will help to diminish massive framerate drops.

What I also experienced when using high frame cap values was stuttering due to sudden framerate drops as soon as some graphically intense area became visible; something that didn't happen at 60 fps. And what would more be good for if you cannot see it anyway?

Another claim that has been made was that frame rate drops weren't as bad when using high frame cap values. Technically that is complete nonsense. The frame rate will always only drop as much as is enforced by computing a single frame, so if you have a 200 fps cap and the current frames needs 40 ms, you will suddenly have 25 fps just as when you have a 60 fps cap. The built-in frame rate display is not a reliable indicator here as it only gets updated three times a second and hence only displays an average. If your framerate is briefly dropping from 60 fps down to 10 and then going back to 60 you will get another average value than when it's dropping from 200 to 10 and rising back to 200.