Also, one thing that makes performance very bad is if you have a lot of subscribed communities is "Subscibed" box in front page and profile page, because it needs to get images for all of those.
I’ve noticed this while working on my client. lemm.ee is the slowest instance out of the 3 or 4 v0.19.x instances I regularly test, specifically with login and loading user profiles. This might be something unique to lemm.ee
On Android, you can use the Voyager app, the only app I have found that works well after the 0.19 upgrade. As far as my linux 'liftoff' app or any other, no longer works. The webpage is also really slow.