Chat messages by a user should be throttled

[lisandre]

A user can use macros to post hundreds of messages per second to the chat. Malicious actors share this information with each other, so the practice is becoming more widespread. When this happens, it affects all other meeting attendants, slowing their devices by demanding more and more cpu usage. In extreme cases, the meeting can be effectively locked by a malicious actor, because the devices of the host and cohost can be slowed to the point of being unusable. A very slight adjustment, throttling a single user to, say, 1 message per 500 milliseconds, would fix this problem without disrupting the chat behavior for virtually all other users.