Definitely looking forward to the release of the new render engine, slated for later this year, with roughly 1 gillion x performance (at minimum). https://community.penpot.app/t/its-time-for-penpot-to-almost-move-away-from-the-dom/6437/8

I'd just use Penpot for smaller stuff at the moment, like a presentation or quick explorations. For images, I also found myself recently resizing and compressing them separately before import. That helped a lot.