Yesterday I installed the latest version (2.3.3) of LyX, together with the latest version (2.9) of MiKTeX.
I'm using a newly bought (two months old) Dell XPS, 4K display, 16GB RAM, 512 SSD, Core i7 8th Gen, running on Windows 10.
When I first opened LyX after installation, I saw that the resolution is wrong - the interface was tiny - the toolbar buttons, the menus and all.
I tinkered with the preferences and managed to enlarge the buttons so they now look normal, but it's clearly only a cosmetic change and it doesn't actually fit the true resolution of my display.
Everything is slow - scrolling and typing have awful response time, to a point where typing and using LyX becomes unbearable.
This happens even though my document is tiny (only ~300 words), and my PC handles heavy programs with ease.
This is also surprising as I've previously used LyX on my old, bad PC which didn't act this way.
I have a feeling that the performance issues are related to the resolution issues, possibly due to the 4K display, but I don't have anything to support this feeling.