Yeah, SQL Server usually handles it better. I know also of MySQL based forums where (and big ones) where this is no problem. It also depends on your web server / database server.
One more question. The archive function is based on the Last_Post date to determined which one shoule be moved, correct?
If I can not use the function, I can create some SQL to do it. I am not sure whetheer this will enhance my fourm's performance. There are not many posts, only like 80K in the reply tables.
80K doesn't seem that much. Seems like the web server and or the database server are not able to handle the load from the inefficient archive script, so not sure that it will make much difference... Probably diminishing the number of records, extending the archive period, would be the best option.