I have install both TeXmacs 2.1 and Xmacs (a fork of TeXmacs, based on TeXmacs 2.1 and Qt5). The scrolling in Xmacs is much smoother than TeXmacs (much like webpage scrolling). Is it because the Qt5 vs. Qt4 thing? Can we compile TeXmacs with Qt5 on M1 chip? Of course, Xmacs has its own issue: inserted pdf images get blurred.
Smoother scrolling?
It may very well be because of Qt4. I build TeXmacs with Qt5 on Linux and get smooth scrolling. However, the static builds from texmacs.org (built with Qt4) have jumpy scrolling.