Jittery scroll with arrow keys and weird flickering

[LazyDevUserX]

• Version 3.5.2 release

When scrolling High Quality Manga (400-500mb) cbz file with arrow keys the the manga panel does a weird flickering and the scrolling is also not smooth.
[ Is there a way to make the arow key scrolling smoother? ]

Steps to reproduce the behavior:

1. Open a HD manga cbz file
2. Zoom in to fit screen
3. Scroll with arrow keys
4. See the flickering

[GitHubRulesOK]

It is a constant problem with different hardware and will be more noticable in some files than others.

SumatraPDF is based upon MuPDF which during render, either only jumps page to page or has non continuous scroll when zoomed in. There the scroll seems to be based on a number of scan lines at a time or would simply be TOO smoothly SLOW !

SumatraPDF has to use that as its base rendering engine.

I loaded a 500+MB CBZ on this slow 32 bit machine which has
Windows default scrolling set to 3 units per move.
I ensured in settings SmoothScroll = true
and used my MOUSE hardware Autoscroll in slo mo[de]
and it does still "jitter" just a little

So setting Windows mouse Lines option to 1, 3 (or 50) does not alter my AUTO scroll. It just affects the normal scroll wheel thus 1 would be best but AUTO is better for me as it leaves other applications (such as Edge) as they expect the default to be at 3.

Generally Windows is set to render several lines at a time which causes the "jitters"

[LazyDevUserX]

My mouse scroll works fine but when using the arrow keys to scroll it's a jittery mess tbh reading manga isn't SumatraPDF's forte