If there are more users at a particular time, the site becomes too slow.
The server is fine.
In particular, when a user downloads using a bulletin board attachment, it is almost down.
The capacity of the attached file is usually about 4mb x 7pcs.
The number of users downloaded is about 100.
This process takes about five minutes.
Is there a time when the site slows down due to the traffic being concentrated in a short time?