CPU spin / lockup when switching rooms

### Steps to reproduce

1. Rapidly try to mark your room list as read by clicking on each room
2. Wait for a lockup to happen

### Outcome

#### What did you expect?

The app to be its normal speed.

#### What happened instead?

The CPU gets warm. Previously this was said to be related to the member count in the room, but disabling the new room header labs flag fixed it. It's now doing it without that labs flag enabled, and does indeed appear to be related to the number of members in the room.

### Operating system

Windows 11

### Application version

Element Nightly version: 0.0.1-nightly.2023090401 Olm version: 3.2.14

### How did you install the app?

The Internet

### Homeserver

t2l.io

### Will you send logs?

No