A first try to solve the issue might be the following patch:
http://home.vr-web.de/~rnissl/vdr-xine-0.4.2-1.patch.gz
It reduces the number of dots written to console to only two (the
first and the last one). Furthermore, it sends no more than 20 speed
changes to xine. These fixes should reduce CPU load dramatically.
No luck, it still does the same.
As far as I have examined the issue, it seems that sometimes (or quite often)
xine's metronom doesn't synchronize to the new stream, or at least it
synchronizes to late. This feature seems to depend on the CPU load too.