Let's say there is an on-line forum, on which its members have regular fellowship. The fellowship hasn't been too active recently. Only two or three messages a day. But the day before yesterday Jack posted a question about cats that made the communication on the forum very active: 25 messages the day before yesterday, 35 messages yesterday, and 20 today. What would be the best idiomatic way to describe this happening in English in the following sentence:

Jack caused a little ____________________ on our forum when he posted his question about cats the day before yesterday.