Optimize manifest.add Testing shows that manifest.add is spending a significant percentage of its time running calcoffsets and doing text = "".join(addlist). This patch removes the need for both of these by storying the manifest in a character array, and using a modified bisect search to find lines without the help of a separate index of line offsets. manifest.add was also reworked to push delta construction/combination into the main loop. Time to apply 2751 patches (without psyco, ext3 noatime,data=writeback): Stock hg: 4m45s real 3m32s user 55s sys patched: 2m48s real 1m53s user 43s sys quilt: 2m30s real 45s user 50s sys (quilt does much more io...)

def demandload(scope, modules):
    class d:
        def __getattr__(self, name):
            mod = self.__dict__["mod"]
            scope = self.__dict__["scope"]
            scope[mod] = __import__(mod, scope, scope, [])
            return getattr(scope[mod], name)

    for m in modules.split():
        dl = d()
        dl.mod = m
        dl.scope = scope
        scope[m] = dl