FFS very slow mtp sync at first run

[CarlosCastaneda]

I sync some folders with my cell phone via mtp and have noticed the following strange behavior:
when I compare the folders on differences, it runs very fast. The first sync however takes ages (in the minutes range), all further ones are again very fast, at least as long as the phone stays connected to the computer.
I did a test with a file to be synchronized and recorded the comparison, the first slow sync and another fast one with Process Monitor. I noticed that the comparison creates about 5 ffs_lock files per directory, the first sync creates 105(!) and the further sync about 6.
Why at the first sync 105 times lock files are created is a mystery to me.