[fnky]

Sketch now runs on Metal—since version 52—and it has greatly improved performance. Your references seems to be very outdated.

[keybits]

Looks like this landed in October 2018: https://blog.sketchapp.com/dark-mode-data-a-brand-new-look-a... There are indeed significant performance improvements.

"Now running on Metal and with a brand new tiling system for the Canvas, Sketch performs better than ever when moving, resizing and manipulating layers in a large or complex document — up to 2.7x faster than Sketch 51!"