#require no-pure A script to generate nasty diff worst-case scenarios: $ cat > s.py < import random > for x in range(100000): > print > if random.randint(0, 100) >= 50: > x += 1 > print(hex(x)) > EOF $ hg init a $ cd a Check in a big file: $ "$PYTHON" ../s.py > a $ hg ci -qAm0 Modify it: $ "$PYTHON" ../s.py > a Time a check-in, should never take more than 10 seconds user time: $ hg ci --time -m1 time: real .* secs .user [0-9][.].* sys .* (re)