grow the list to its final size once, at the start (overestimating if you don't know for sure). Then instead of appending, keep an index to the next free slot, same as you'd do in C. Then the list guts never move, so if that doesn't yield the same kind of speedup without using LFH, list copying wasn't actually the culprit to begin with.
If this *does* improve the performance of his application by 15%, that would strongly argue for an addition to the list API similar to Java's ArrayList.ensureCapacity or the STL's vector<T>::reserve. Since the list implementation already maintains separate ints for the list array size and the list occupied size, this would really just expose this implementation detail to Python. I don't like revealing the implementation in this fashion, but if it does make a significant performance difference, it could be worth it.
http://java.sun.com/j2se/1.5.0/docs/api/java/util/ ArrayList.html#ensureCapacity(int)
http://www.sgi.com/tech/stl/Vector.html#4
Evan Jones
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