Comment 18 for bug 1308037

So from looking at the log:

23.19s - Unity queries applications masterscope
26.37s - apps scope appears on bus
43.49s - BAMF query for running apps
43.58s - Search invoked on apps scope
48.20s - Search inside apps masterscope timed out, sent no-results reply
52.30s - Search in apps scope finishes

So on your machine it took the apps scope ~20 seconds to initialize and start processing requests, and then another ~9 seconds to process the first request, which is pretty bad, cause the dbus timeout is 25seconds. Although from the log it's also visible that the apps scope did respond to further searches, I assume the case where it doesn't work at all is when the initial initialization itself takes more than 25 seconds.

All in all, I'd attribute bad IO performance to this issue, but clearly the apps scope should handle that better.