huge slowdown on append

[Fredrik Lundh]

ianaré wrote:

>> I changed it to this:
>> items_ren.append([join(newPath,renamedItem), False])
>>
>> And processing speed is now much much slower. For 5780 items the old
>> function would take 9.5 seconds (there is other stuff going on
>> obviously), after changing that single line, speed is now 55 seconds
>> in the same conditions!

have you checked the process size?  short lists are relatively expensive 
to create, both performance-wise, and more importantly, memory-wise. 
try using tuples instead.

or better, move the flags to a separate data structure (either a list, 
or, if possible, a set or dictionary keyed on filenames).

</F>