In case anyone else views this topic:
I noticed in recent testing that Chrome is 2-10x faster at rendering thumbnails than Firefox, at least on Linux. It pains me to say this, but you might want to try Chrome.
I’ve also made some front-end performance improvements to image loading in the latest v1.0.0-beta builds (we’re now using the browser-native lazy image loader if we’re not on safari), which seems to have helped as well.
There’s also a new advanced system setting to host your .photostructure/previews
directory on a separate SSD: I just wrote this up here: