Hi, I "solved" the problem. The process that was taking up the CPU wasn't "amarokcollectio" but "amarokcollectionscanner" (truncated with top :/). It was not very clever not to think of running it... So I run amarokcollectionscanner in a terminal and I discovered the scanner was stopping on a specific file. It seems that that precis file was corrupted. I moved it away of the music directory and this solved the problem.
However I suppose that could be considered as a bug in amarok, but I can't provide any information more and it's a very particular case, so it would certainly be a good idea to close this bug report. Sorry. Nicolas
