Refactor polling on the question overview
Currently, all questions on the question overview (https://frag.jetzt/participant/room/.../comments) are polled every second. This is a huge traffic, considering sessions with many questions and many online users. As a quick workaround, the interval should be extended (e.g. to 5-10 seconds) or only applied for moderators.
In the long run, this behavior should be refactored and implemented with websocket.