Comment 138 for bug 578215

If you want to "use" nepomuk you have to remove its database from time to time. You will lose your tags etc. and you might have high CPU usage because it re-indexes all files – but at least that cpu usage ends at some point. And to be honest, nepomuk is of no use as desktop search anyway, compared to state-of-the-art desktop searches.

Sadly it happens very often that at some point or after an upgrade from KDE 4.x to 4.y virtuoso uses the cpu constantly, never comes to an end.

There are some hints at http://kdeatopensuse.wordpress.com/2011/11/09/debugging-nepomukvirtuosos-cpu-usage/ on how to debug.

But as I mentioned, the quickest way of getting around that buggy piece of software is to just remove its database from time to time. Does not sound nice and I wish it was different, but these issues have been around for years and are still not resolved.