xml files of Brevecreatures slow down the program.

I don't know whether this is a bug report or just a remark / feature request about the file handling of the program. However, I noticed that the xml file of creatures.tz grows in time, and that, after every tested creature, the file is completely rewritten.

This is not anything to notice as long as the Generation number is low. However, after a long-run simulation, it massively slows down the speed of evolution (I have, for example, a still growing 30 MB big xml file on the hard disk whose writing process takes around twice as much as the fitness evaluation process, i.e. it thirds the evolution speed). What causes the growth of the file? Does it store all the past generations as well? And why does it rewrite the whole content instead of changing the last saved generation? Is this kind of a bug or something essential for the program to work? Or am I using the wrong setttings somewhere?

Thanks and best regards