Huge CPU peak when opened
Probably due to the rendering of the fonts, opening this program causes lags and freezes even on fairly powerful machines. My guess is that this is caused by the "concurrent" rendering of lots of fonts. Having fonts rendered one by one in order (or perhaps X-by-X based on CPU cores, but that is more complex), like the Photos app does, would avoid such lags from occurring. Please see the attached screencast on Fedora 29, GNOME Shell 3.30 and an i7-8550U CPU