Replaced fixed window size for walkchangerevs with an increasing one. Window sizes starts at 8 (for good interactiveness) and doubles with each window until it is 512, which seems to be the maximum efficient value.

#!/bin/sh

hg init a
cd a
echo a > foo
hg add foo
hg commit -m 1 -d "0 0"
rm foo
hg remove foo
hg commit -m 2 -d "0 0"
hg export 0
hg export 1
hg log -p -r 0
hg log -p -r 1

cd ..
hg clone a b