That lag is Windows changing the wallpaper. At the moment, there is nothing you can do to speed it up.

I have an issue I can't quite resolve.

When I have dexpot configured with custom wallpapers for each desktop, I experience a slight pause when switching between each desktop view.
I'm running dexpot on a 2560x1600 monitor, so native res wallpapers are a bit large at 3mb, but my PC is more than capable of handling hundreds of such images loaded onto photoshop for example with no issues.
Is there anything I can do on my end to get separate wallpapers running smoothly?

specs:

intel core i7 3930k
16GB 1600mhz ram
nvidia gtx580 graphics card /w 1.5GB ram
samsung 840 SSD