Also tried it on my side, on fresh created document it’s smooth with most brushes at 1000px; didn’t tried above.
I get some lags with more complexes brushes.
Also, hardware is very important; 24CPU doesn’t mean that it will be faster.
Here some posts about case I’ve got:
In synthesis when you have a lot of CPU, you also need to have a very fast memory otherwise there will be a bottleneck and finally you’ll get worst performances than using less CPU.
On my computer optimal number of CPU if 22 of 24…
