I recently noticed that if I log in to my xfce GUI straight after powering up my computer it takes an inordinately long time. Like it takes four or five minutes from when I enter my name and password to when the desktop appears completely.
After suspecting that there was something awry with my X startup (such that it was doing something odd the first time it was run) I realised that it was simply that the system was very heavily loaded by something during/after boot. Watching the load average during the X startup it went over 8 whereas if I login to X after the system has been running for some hours the load average reaches the giddy heights of 0.14.
With a load average of 8 things almost grind to a halt, some processes retry starting (I get more than one xfdesktop for example) and update-notifier times out trying to access repositories which it has no problems at all with if I log in later.
Another symptom is that some nfs mounts haven't completed before the terminal windows appear on the desktop so when I run mutt (mail program) which uses one of the NFS mounts it fails to see its mail directories. That's seriously wierd.
I've tried to analyse what's going on by running top (and 'w' and ps) in a console window while the system starts up but I really can't see anything obvious that's hogging any resource. One noticeable thing apart from the load average being so high is that my 8Gb of memory gets eaten up too, but there seem to be no particular processes using either lots of CPU or lots of memory.
Can anyone suggest further ways of trying to diagnose this?