Moving text cursor around a document slows down Inkscape performance

Main problem: When moving the text cursor (F8 or T) Inkscape slows down to a crawl.
CPU (the one thread that Inkscape uses) remains at 100% for at least 5 seconds every time I move the cursor from a text box to the edge of the document, say towards the Selection tool in the upper left corner or from the selection tool to the text box.
File size where this happens is 21.0 MB, saved as SVG.
There are other text-boxes in the trajectory followed by the cursor, as well as vector graphics.
If I by-pass them and move the cursor rapidly outside the document, reaching my target (e.g. the selection tool) moving only through the toolbars that are outside the editable part of the document, the slow-down does not occur.
It appears, thus, that even by passing over an object (text or vector graphic) while equipped with the text cursor Inkscape tries to "preload" somehow these objects, but slows down a lot (I think, partly, because one CPU thread is not enough).
The bug occurs on both Gnome 3.10 and Gnome 3.10 Classic.

Possibly related bugs:
https://bugs.launchpad.net/inkscape/+bug/1219794
https://bugs.launchpad.net/inkscape/+bug/497094

System:
~$ uname -a
Linux polarBear 3.13.0-29-generic #53-Ubuntu SMP Wed Jun 4 21:00:20 UTC 2014 x86_64 x86_64 x86_64 GNU/Linux

Intel Core i7 CPU 960 @ 3.20GHz (4 cores/8 threads)
24 GB RAM
GeForce GTX 560Ti
OCZ-AGILITY2 90GB SSD

Inkscape 0.48.4 r9939