Comment 1 for bug 631771

 I think I've a fix for this.

 Removing tasks in my test version takes : "DELETING 200 NODES: 0.045737".

 I found with profiling that the function that took the most time was: reordered of module of tree_testing.py (14 sec. on my pc.)

 So I think I removed the need for this, my code passes all tests (Except the one for date, because my locale is french.), and I was able to remove tutorial taks. (This means a task with children). I've no idea how I can further test this, so I'm attaching a patch, that would be better to try in another branch to avoid my other error. (With dates.py)

 Posting patch in 2 mins.