High CPU utilisation on Xorg when fsck is running
I'm running into a situation where my system's CPU utilisation jumps from near-zero (1-5% during idle runtime) to 40-60% (I've seen as high as 63%) while fsck is running on my second HD. The odd thing (to me) is that the CPU utilisation as seen by top and system monitor as being tagged to the Xorg process. I'm invoking fsck using 'sudo fsck.ext3 -cf /dev/sdb1', and once it hits the 'Checking for bad blocks (read-only test)' step is where it spikes.
The system is equipped with a P4 3.0GHz Hyper-threaded CPU, a little behind the times for sure. Running with Ubuntu 9.10 in GNOME. I've also caused the same spike in CPU usage by opening an SSH session from my mobile phone, invoking the same command as above, with the same results (further puzzling me, since I can't figure out why Xorg would get involved on a command issued by an SSH user).
Is this near the norm for this sort of command, or is something going a bit awry? I hesitate on letting this rig run with such high CPU usage, seeing as I have trouble getting memtest86 to complete (due to overheat) without starting it from a cold boot; I've seen that a bad block check like this can get rather lengthy.