annotate: do not construct attr.s object per line while computing history Unfortunately, good abstraction has a cost. It's way slower to construct an annotateline() object than creating a plain tuple or a list. This patch changes the internal data structure from row-based to columnar, so the decorate() function can be instant (i.e. no Python in hot loop.) For code readability, the outermost tuple is switched to an attr.s object instead. (original, row-based attr.s) $ hg annot mercurial/commands.py --time > /dev/null time: real 11.470 secs (user 11.400+0.000 sys 0.070+0.000) $ hg annot mercurial/commands.py --time --line-number > /dev/null time: real 39.590 secs (user 39.500+0.000 sys 0.080+0.000) (this patch, columnar) $ hg annot mercurial/commands.py --time > /dev/null time: real 11.780 secs (user 11.710+0.000 sys 0.070+0.000) $ hg annot mercurial/commands.py --time --line-number > /dev/null time: real 12.240 secs (user 12.170+0.000 sys 0.090+0.000) (cf. 4.3.3, row-based tuple) $ hg annot mercurial/commands.py --time --line-number > /dev/null time: real 19.540 secs (user 19.460+0.000 sys 0.080+0.000)