Is it possible to automate the script

The Re-sync Topic and Post count tool should never need to be manually run, infact I can't remember ever running it on this forum. It's only there incase any forums or posts show incorrect last post or last post member. A smaller lightweight version of this function is run each time a new posts/topic is made or deleted in a forum.

The forum should not slow down no matter how many posts are made. The issue you mention sounds like an issue with the mail server becoming over loaded. Each time a message is posted email notifications are sentout, if the mail server is starting to respond slowly then it will slow down the speed at which the page is refreshed after making a new post.

Have you disabled email settings from the admin area?

50 Posts in 10 minutes should have no effect, as it only takes around 0.2 seconds to save the post, once this is done then any resources used to save the post are released.

Unless you are using Access. Access is a desktop database and not able to handle lots of concurrent connections due to it's limited abilities and is only available for non-production testing. If you are using Access you should look at upsizing the database to SQL Server.

Did you read the rest of the post?

Then you should see no performance issues from 50 posts made in 10 minutes.

If your forum is slowing down then you should look at other things like network congestion issues and server load.