Performance tuning KDE

disable Strigi
===============
System Settings -> Desktop Search
There are 2 components to Nepomuk.

The component that sucks up CPU and IO is the Strigi file indexing service.
This extracts metadata from files.

The second and more important component is the Nepomuk metadata service.
This is where the file indexer stores metadata, but also, applications using the nepomuk libraries can store arbitrary data.

If you disable all of Nepomuk, KMail will not be able to do email address completion from your address books,
or distribution lists, file rating and tagging will not work.

By disabling all of Nepomuk you save about 50MB for the virtuoso database backend but very little CPU and IO.
You can disable Strigi on its own if you don’t care about file search and indexing.

http://www.freetechie.com/blog/disable-nepomuk-desktop-search-on-kde-4-4-2-kubuntu-lucid-10-04/