log: cache diffopts instance It appears that calling patch.diff*opts() repeatedly has some cost. $ hg log -T '{rev}\n' -R mercurial --time > /dev/null (orig) time: real 4.430 secs (user 4.370+0.000 sys 0.050+0.000) (new) time: real 1.950 secs (user 1.880+0.000 sys 0.060+0.000) 'diffopts or {}' isn't necessary as patch.diff*opts() accepts opts=None.