Rooms with lots of hidden events render very slowly #21740
Description
Steps to reproduce
Visit a room with 100s of hidden events
Outcome
What did you expect?
Fast rendering
What happened instead?
Slow rendering, due to hitting the setting store for every hidden event on every render. This is a regression, and we should test that timeline rendering doesn't do localstorage I/O / settings lookups, so this doesn't happen again.
Operating system
NixOS unstable
Browser information
Firefox 98.0.2
URL for webapp
develop.element.io
Application version
Element version: cec31d0-react-f648140d0c72-js-3b33237e51ae Olm version: 3.2.8
Homeserver
Synapse 1.56.0
Will you send logs?
No