Is your laptop set to conserve power?

Often the graphics card on a laptop is set to use as little power as possible on the desktop and only speed up in games.  Some even use the intel onboard graphics on the desktop and only use the powerful card when it detects a game.  This tends to impact performance somewhat.

Also what resolution are you using?

My laptop is on maximum performance and the processor uses an integrated Intel HD Graphics 530 when the 980M is not being used, which should handle the UI tweaks the WindowsFX offers... The feedback on WindowsFX from other people with hardware configurations different from my own indicates the problem is with the software rather than the hardware.

Unfortunately if you experience performance slowness the instant you enable the software it is highly probable that the issue is that your machine hardware is simply not up to the task.

All too often the video drivers are set to downclock the graphics to the lowest possible setting to save power and only increase clock speed when they detect a game is running.  As WindowFX does animations etc very briefly they often fail to detect it quick enough and so end up running slowly.  This is outside our control.

Machines with multiple graphics adapters also suffer from a problem with the wrong adapter being picked causing massive transfers of graphics data between the two graphics processors.  I cannot recommend machines with that kind of setup for WindowFX or DeskScapes as they will be very inefficient.  Those hybrid laptop setups also tend to be the cause of many a game crash.

If the slowness happens over time there could be something leaking which could therefore be fixable.

Something you did not answer is that resolution are you running at?  If it is top of the line I assume it is pretty high indeed.

A significant part of the issue is your resolution.  How many of those games are you playing at 60fps on the Intel Graphics?

As a quick test, if you lower resolution to say half that does it all work a lot smoother?  Obviously you wouldn't do that usually, but it would decrease the load on the graphics hardware by a factor of 4.

In terms of what works, any computer with a standalone graphics adapter running at a reasonable resolution should work just fine.  Integrated graphics tend to not be up to the task and very high resolutions will make that worse.

As an additional thought, does the bios have an option to disable the integrated graphics completely and always use the NVidia?  Note that forcing WindowFX via NVidia settings will not help as multiple processes (dwm.exe and explorer.exe) would both need to use the very same processor or the impact would be negative.

I can't say I've even known of, or expected to - have an integrated graphics adapter that could push 3840x2160.  If one did it would be unlikely to make it to 60hz.

If your laptop was set to ONLY run with the 980M I expect everything would be 100% trouble-free....