When logging out of your desktop session, you want all programs to shut down quickly. Strigi is one of the programs that can linger while it is analyzing a file. I've done some work to improve this latency and have measured the current latency after some improvements to analyzers that can potentially take long on some files.
Here is a graph with the analyzer latencies of my current version:
You can see that there is a 5% chance that stopping an analysis takes more than one second.