I use a Vollaphone, a GS290 (equivalent) and an Xperia 10ii. The 10ii is certainly not as performant as the other two.
I’d say SFOS is pretty snappy, although the introduction of sailjail has slowed down OPENING apps a bunch. I think these are optimizations that fell by the way side but should be doable.
The browser is also not stellar, but neither is web.
I often do image/video work (leaning on either python or ffmpeg) and get quite speedy results (comparing my stopmotion app, for instance, with a similar app on a friends iphone 11x which is a better phone).
I think the Jolla team has too many irons in too many fires to do some of the usability work. But I have hope. Bug triage (thanks to @thigg, @pherjung & co!) have been helping focus things…