design – What does Stackoverflow comment system work

When someone comments on my question/answer/comment I will see the notification from the inbox, and it also shows under my response tab. Later when the comment is edited, the comment shown under the response tab changes; when the comment is deleted, the comment disappears from response tab as well. And the inbox message updates correspondingly during the process.

I think the system sends the notification through the queue service, and at the same time push the comment to my response tab. After that my account tries to pull the system periodically to update any changes (edit/delete). Is my understanding correct? Will it be a bottleneck for the system if so many users account pulls at the same time?