Afaik, you have these options:
1. Place everything on one row in the table.
2. Send stacked queries (by adding them after each other within the same string). I don't know how the AMXX SQL core will handle it though. It may split them before sending.
3. Send the SQL queries instantly instead of buffering them until the end of the map. The count will increase, but the stream will be more even.
4. Store the information locally in a file or a vault before mapchange and then once the map starts, send the stored queries one by one.
Personally I would experiment with the fourth option because it sounds interesting.