After what refresh rate did you stop feeling the improvement in smoothness?

[Inco^]

360 Hz on XL2566K was already pretty smooth, but 540 Hz on PG248QP is even smoother, to my eyes. Experienced this on a game with >540 FPS.

just out of curiosity , what games do u have >540FPS in ? and what are ur specs

Medal of Honor Allied Assault (MoHAA).
Dead game but competitive scene got revived due to covid.

I don't have 540 FPS in any other shooters, so my specs are pointless. But here you go:
i9 12900KS / DDR4 3600 MHz CL17 / RTX 3080

[Sirius]

If you have a screen at high refresh rate which have a bad refresh compliance it could be hard to tell a difference because the screen are not compliant with the refresh rate.

[masneb]

You notice it when you go to the higher end, then come back for sure. Have a 540hz and it was immediately noticeable. How much is refresh as opposed to a better panel is a good question too. Haven't tried OLED due to burn in issues.

Slow panels with fast refreshes look like smeary fingerpaints.

[Cwuster12]

So, after making some observations, it seems to me that the point of ideal smoothness starts from 160-180 frames per second