context: avoid extra parents lookups...
context: avoid extra parents lookups
Resolving parents requires reading from the changelog, which is a few
attributes and function calls away. Parents lookup occurs surprisingly
often. Micro optimizing the code to avoid redundant lookups of parents
appears to make `hg log` on my Firefox repo a little faster:
before: 24.91s
after: 23.76s
delta: -1.15s (95.4% of original)