shouldn't be installed on weak machines (update-apt-xapian run by anacron is a disaster)

After installing Ubuntu 12.04 on a Toshiba AC100 a couple of months ago, as described at https://wiki.ubuntu.com/ARM/TEGRA/AC100 , I experience a disaster from time to time when working with my system: update-apt-xapian is being run by anacron, and it consumes a lot of memory and CPU, so that nothing is usable on the desktop:

from pstree:

     ├─anacron───sh───run-parts───apt-xapian-inde───update-apt-xapi───cat

from top:

  PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND
   20 root 20 0 0 0 0 S 5 0.0 4:35.12 kswapd0
   48 root 20 0 0 0 0 R 5 0.0 2:01.26 mmcqd/0
 4793 root 39 19 387m 154m 1368 D 4 35.4 11:34.26 update-apt-xapi
 4832 root 20 0 0 0 0 S 2 0.0 0:12.02 kworker/1:2
 1304 root 20 0 58272 15m 1344 D 2 3.5 10:54.36 Xorg
 2545 imz 20 0 110m 5260 2484 D 2 1.2 4:50.38 unity-2d-panel
 2827 imz 20 0 511m 20m 1384 S 1 4.6 24:14.28 firefox
 4896 root 20 0 2156 700 400 R 1 0.2 0:00.31 top
 2563 imz 20 0 63200 3460 1692 D 1 0.8 9:01.60 indicator-multi
 2618 imz 20 0 72632 5100 1548 S 1 1.1 14:49.22 unity-panel-ser
 4811 root 20 0 0 0 0 S 1 0.0 0:08.21 kworker/0:1
 4819 imz 20 0 65508 2524 1364 S 1 0.6 0:22.86 emacs23

It mustn't be installed by default in the variants of the distro for such little machines as Toshiba AC100.

ProblemType: Bug
DistroRelease: Ubuntu 12.04
Package: apt-xapian-index 0.44ubuntu5
Uname: Linux 3.0.27-1-ac100 armv7l
ApportVersion: 2.0.1-0ubuntu11
Architecture: armhf
Date: Thu Aug 16 17:13:47 2012
PackageArchitecture: all
SourcePackage: apt-xapian-index
UpgradeStatus: No upgrade log present (probably fresh install)