Shaders Impact on Smoothness

I find this issue confusing. With "FSRCNNX_x2_8-0-4-1.glsl" on 1080p content, I have 0 frame drops and 0 delayed frames when watching content. But in panning shots where the camera is moving from left to right or in the opposite direction, the impact on smoothness very clear. It looks choppy, or not smooth at all, but there is no dropped frames. I actually hadn't noticed it much until I watched the latest episode of Game of Thrones, at the start when the boy is looking over the tree and the camera pans from right to left, the scene feels like its skipping, not happening in one smooth motion, but move and chop, move and chop, all the way across. I remove the line below and its smooth, but in both instances there is no dropped or delayed frames. Why does that happen? Of course GPU usage is much higher with the Shader below, but it should be fine, as the GPU is not hitting 100%, it hovers at around 70% to 80% usage with it, and around 25% without it. GTX 1070, upscaling to 4K TV.

profile-desc=cond:get('height', 0) < 1440
glsl-shader="C:\Users\musta\AppData\Roaming\mpv\Shaders\FSRCNNX_x2_8-0-4-1.glsl"