Windows 10: GTX 960M w/ 4K Computer not working well on 2K monitor

So I'm using a 4k laptop with a 2560x1440p monitor. My graphics card is a GTX 960m. I have the drivers and all that but for some reason i can't use it to its full advantage on this 32 inch 1440p monitor, as with high settings on games it gets all choppy and suffers low fps.
My theory was, if I use this 4K computer with a LESS than 4K monitor, than the performance should be just fine. But no, it's definitely worse than my 1080p monitor I used to use this 4K laptop with.
Before all this, I had tried a 1080p computer with a 4k monitor, and graphics performance suffered. I thought it was just because I was scaling a 1080p computer onto a 4k monitor, and of course the graphics quality would suffer drastically.
Can anyone explain if my theory was wrong or if I'm doing something wrong?

:)

 

Slideshow - previous image flashes on transition

During a slideshow - either a millisecond prior to the end or just after the transition to the next image, the previous image flashes on the screen over the new image - though not usually the whole screen - more like the lower 1/3, 1/2 or 3/4 of the screen
- the location is random, but it happens during every transition as described below. Here is a video of it happening:

It is not a power issue (1200 w PSU, 4.7 ghz processor, 32 gb ram, gtx 980 ti). It is most definitely a high resolution issue.

I've found two links that describe the problem - one person is using another program to show a slideshow (display fusion) and the other is using the native windows 10 slideshow. The common denominator is a 4k monitor. (I also use Display Fusion and have tested
that it occurs with both DF and the native slideshow.)

In my case, I have two 4K monitors and two 2k monitors. On my 1920 x 1080 2k monitors, the flash does *not* occur. I can confirm that it is only on both 4k monitors. I can also confirm that lowering the resolution on one of my 4k monitors prevents it from happening
on that same 4k monitor. I also tried changing to an image folder with lower resolution pics without success. So it is Windows trying to deal with the high resolution of the monitor that seems to be the problem.

When I disable animation elements in windows (System>>Advanced System Settings>>Performance) it cuts right to the next image without the transition effect - so there is no flash.

 

Screen Resolution

Quite right, 2K is in reference to 2560X1440 (16:9) and similar resolutions, including
2560x1600 (16:10).

Are you trying to run the laptop at 2560x1440 to match the 2K monitor ?

Does your 4K laptop screen have a native 4K resolution that is 16:9, or is it a 16:10 aspect ratio (Is there a 4K res @ 16:10) ?

If it's native res is 16:10 I would think you could still access 2560x1440 but you may get black bars top and bottom, depending

on how you have setup screen scaling in your graphics processors control panel.

Or maybe not ? Laptops may not be as flexible as desktop ?

- If it's the 2K monitor you are trying to set the resolution on, and assuming you have highlighted monitor 2 in
Display Settings

without success, does it help if you switch to Show Only on 2 ?

.

 

I doubt that a 960M (950M, as in your specs?) is adequate for gaming at 2560X1440. The fact that it's OK for a 2D display at 4k does not imply that it'd have enough power for 3D games at 2k.