after setting up the akonadi/kmail/kontact family, I experience frequently high cpu load, which is not nice for battery life and makes the fan in my laptop sound like a vacuum cleaner

top says the culprits are mysqld, akonadiserver and nepomukservices. nepomuk I had activated before trying kontact, and it was not a cpu problem before. Also currently it is not indexing files as I checked.
Is there any way to figure out why these processes are so busy and how to make them calm down?

To understand the problem, here are a few questions:

- How many accounts do you have? How many messages (an approximate count)?
- Do you have email indexing enabled in System Settings > Desktop Search?
- Which version of KDE PIM are you using?

My guess is that it is indexing your mail, a potentially time consuming process (although it is faster in 4.10.x).

BTW, there is no "nepomukservices" executable: I assume you meant "nepomukservicestub" (being phased out for 4.11), because "top" and similar tools truncate its name.