Large brushes lag with stylus, fine with mouse

[Ratty]

Hi,
I'm using a Surface Book 3, with GTX 1050, 8gb RAM, Windows 10, latest drivers and versions of everything installed.
When I use large, fairly complex brushes (in this case, from the True Grit Texture Sampler, 2500p brushes), they work very very slowly with the stylus. The brush preview is about 30 seconds behind, and when I click, it is unresponsive for a good minute or two. If I use my trackpad instead of the stylus, it's fine (a touch slow, but only half a second or less, understandable with such large brushes).

Using a stylus, it even lags so much that when I hover the stylus over the canvas (showing the brush preview), I must wait for 30 seconds or so before I can use any of the menus or panels again. (With the trackpad, no problem).

EDIT -
This also only seems to be a problem on smaller canvases. If I set a canvas to 5,000 x 5,000 pixels, 300 dpi, it's slow with the stylus (normal with trackpad). If I set the canvas to 50,000 x 50,000 pixels, 300dpi, it's much much faster with the stylus.

I tried disabling all stylus-based brush dynamics (pressure etc), but the problem persists. It is also the same for Windows ink, low performance and high performance tablet settings.
It's not a huge pain, because I can just use the trackpad for these large brushes, but I thought it might be handy to mention here and see if anyone can help.
Cheers!

Edited April 8, 2021 by Ratty

[stokerg]

Hi @Ratty,

Sorry for the delay in replying to your post.  We were extremely busy when you posted your question and are just catching up with the last of the backlog of tickets now.

Are you still having this issue with the latest version of Affinity?  

[Ratty]

Hello,
No problem, it doesn't affect me very often so I'd kinda forgotten about it.
Yes, I'm using the latest version of Affinity Photo.
I've looked into it a little more, and it's NOT about canvas size, as I thought, but about zoom. It's about how big the brush appears in the window.
In other words, the brush looks a lot smaller on a large canvas than on a small canvas, so large canvases work more smoothly. If you zoom in so the same brush takes up the same amount of space in the window, a big canvas lags too.

CPU and brush details below. The brush is a True Grit Texture company one, with all dynamics off. Canvas is 5,000x5,000px, 300dpi.

If I zoom in so that the brush preview cursor takes up all of the visible canvas (brush size 2500px) move the cursor onto the canvas and click 3 times, then move off the canvas and select a different tool, with the mouse the whole process works instantly, or almost instantly.
With the stylus (tapping 3 times), it can take several minutes. Just now it took about 4 minutes (I couldn't use Affinity in this time - it was 'thinking') and froze up the whole computer for about 30 seconds.

If I zoom out so the cursor looks tiny on the canvas, the stylus works with very little lag.

Again, it's not a huge deal, I can use the mouse, but maybe it's worth your knowing about.