Hello.
I have an SQL server 2012 running on a 32-core IBM machine with a database having 100M rows in a few tables with a couple of columns in each table. The queries performed well with 100% utilization of the cores. However, in one of the bulk data updates of the database the queries started performing very bad with 10 times slower performance.
I carefully checked that there was nothing strange with the last updates. They were just ordinary data updates. But for some reason the same queries do not effectively utilize the full power of the cores anymore. I checked for defragmentation and there were no issues. The disk is very fast SSD and the system memory runs stable around 30GB out of 96GB.
What could be the case of the queries not utilizing the full core-power anymore?
