Edit: I'm writing this out of my ass, so don't quote me.

They wrote that they GPU(I?)-accelerate the font rendering. Well, indeed, fonts are usually rendered with CPUs because it's slow to use the traditional VRAM (which sits in the GPU) for this task, given that the text itself is stuck in the RAM (sitting right next to the CPU). With integrated chips like the Apple Silicon, it probably makes sense to move the font rendering into the GPU because the memory is unified. GTK is absolutely not designed to do this, AFAIK.

But that also means that, to get this particular benefit of their dedicated GUI framework, you probably have to buy an Apple Silicon Mac. There are PCs with similar architecture, iirc, but that also means that there's no way you can upgrade your GPU or RAM individually in the future... My fear is that, on a standard PC, it might be just as responsive as other editors.