Comment by BlurBusters

Alas, software, and operating systems full of stuff sometimes does it...

This CRT simulator almost requires a dedicated GPU (AMD, NVIDIA, Radeon) and nothing running in the background, since it's a software-based simulation of a CRT tube. It is probable that an Intel integrated GPU from 2017 won't work, and neither will a cheap $200 Android phone do it smoothly.

It is doing almost 100 math computations per subpixel per refresh cycle, in a multi-gigaflop supercomputer called a GPU, so if you're running at 2560x1440x120x3, that's still blows past a lot of dedicated GPU abilities, as it's needing to do it on every native Hz, regardless of the low simulated Hz.

Make sure you don't have any software running in background (not even browser tabs, no system tray apps, exit your RGB animation apps), and run in Performance Mode (not Balanced Mode or Low Battery Mode).

It's frame drop-free on my Razer laptop in a clean Windows install, but it starts stuttering with an old Windows install. Not much I can do about operating system preventing realtime stuff.