[Haleth]

I see. Still, better to calculate the optimal value and set it to that.

I use this now:

local scaler = CreateFrame("Frame")
scaler:RegisterEvent("VARIABLES_LOADED")
scaler:RegisterEvent("UI_SCALE_CHANGED")
scaler:SetScript("OnEvent", function()
	if 768/string.match(({GetScreenResolutions()})[GetCurrentResolution()], "%d+x(%d+)") < .64 then
		UIParent:SetScale(768/string.match(({GetScreenResolutions()})[GetCurrentResolution()], "%d+x(%d+)"))
	end
end)

(Registering UI scale change because I switch in and out of windowed mode a lot)

And everything works fine! (well, my GPU diode is chilling at 85°C but that's a different story...)