To be fair, this client is running about 1.5TB worth of databases in TDE. The impact is felt in about a 10% rise in cpu, and a 20x increase in number of locks and lock wait time. A lot of that is to do with the SQL workflow for their applications. And another big part of that is the demands it (encryption) places on tempdb.

As the indexes fragment throughout the day, the impact becomes more obvious. We will see continual slowdowns throughout the workday as the indexes get closer to 30% fragmentation.

Defrag the indexes and we are good for a little while. Disable tde and we are good for a long while.