develop.element.io freezes while opening rooms

### Steps to reproduce

Since today, this wasn't happening yesterday

1. Open develop.element.io
2. Click on a room, in my case #matrix:matrix.org seems to reliably reproduce the issue
3. Wait for a bit as it loads the timeline
4. See that the entire chat timeline freezes and after a while it unfreezes itself

### Outcome

#### What did you expect?

Should not freeze

#### What happened instead?

Freeze

### Operating system

Fedora 39

### Browser information

Firefox Nightly 119.0a1 (2023-08-30)

### URL for webapp

https://develop.element.io/

### Application version

Element version: 1ada110fed0e-react-45094bda7c00-js-5ddd453699a3 Olm version: 3.2.14

### Homeserver

matrix.org

### Will you send logs?

Yes