I don't have any particularly helpful advice to offer, unfortunately, but I can confirm from personal experience that certain queries can indeed bring your system to a crawl. I don't think there's a solution to this unless there's a way to firewall report queries from the rest of Koha, or to automatically throttle misbehaving processes. In my case, I'd copied & pasted a report from the wiki, but a change in Koha's database structure since the report's creation led to, well, very bad results. I think your best bet is to take a really close look at the report to see if there are ways to achieve the same results more efficiently. In our case, this means seeking help from folks who are far more experienced with SQL than we are. Best of luck! Cab Vinton, Director Plaistow Public Library Plaistow, NH