So for the last couple of months i've been having trouble with my brush krita not registering my brush strokes on my tablet, i've tried uninstalling and reinstalling 3.1.4, i've worked with the performance settings, and many other things but nothing is working. I usually test it out once each change by opening a 1000x1500 px document at 72 dpi, but nothing works, can anybody help?

specs:
I use an ASUS 15.6-Inch LED Laptop with a Intel HD Graphics 4000 graphics card, windows 10, i5 2.50 Gz

At those minuscule document sizes, you shouldn't be experiencing any kind of lag, unless your computer is overloaded with other processes or you're accidentally using 32 bits floating point as your channel depth.

Try disabling/enabling Instant Preview Mode in View options.