xterm-title 'flooding'

About two months ago I noticed that under heavy CPU load my system went into a state that made it almost unusable; All processes were still doing what they were supposed to do but input from mice and keyboard were only accepted after large delays (5-20min/key).
Today I finally found out what causes the symptoms:
I use MOC in the rxvt-unicode terminal emulation because it supports unicode and pseudo-transparency. I let MOC set the terminals title.
Whenever I listen to streamed music, the title in my window managers (fluxbox) taskbar begins to flicker as if MOC tries to update the title just every time it can. This does not happen with, for example, xterm. I cannot pin down what parts of my system changed two months ago.

I guess this is more a bug in rxvt-unicode but maybe there could be some minimum delay setting for MOC when updating the title ? My current 'solution' is to disable title setting by MOC.