MyBB Community Forums

Don't post those kind of details here.

If you have a bad setup, just change it. Modify your configuration to what best suits you and your site. If you haven't already, switch to a VPS. Ultimately we can't tell you what is a good configuration, and if you have no idea what you're doing, I suggest you hire someone who does - or find a good host that can help you get setup.

how do i change it? i'll lose 20000 members straight away, in addition to around 40 to 50000 posts.

1. OP stated to me he deleted default MyBB indexes from his tables.

2. OP stated he has about 13k attachments.

Both are imho factors that might be part of the problem.

Missing indexes are guaranteed to roof your SQL query memory usage by a lot.

the indexes were those ones which labrocca had deleted for his forum, for optimization. I followed his innodb article on vbum.com.