hgweb: compute changeset parents and children for log pages lazily Log pages, i.e. changelog, filelog and search results page computed children and parents for each changeset shown, because spartan hgweb style shows this info. Turns out, computing all this is heavy and also unnecessary for log pages in all other hgweb styles. Luckily, templates allow an easy way to do computations on demand: just pass the heavy part of code as a callable and it will be only called when needed. Here are some benchmarks on the mercurial repository (best of 3): time wget http://127.0.0.1:8021/ before: 0m0.050s after: 0m0.040s time wget http://127.0.0.1:8021/?revcount=960 before: 0m1.164s after: 0m0.389s time wget http://127.0.0.1:8021/log/tip/mercurial/commands.py before: 0m0.047s after: 0m0.042s time wget http://127.0.0.1:8021/log/tip/mercurial/commands.py?revcount=960 before: 0m0.830s after: 0m0.434s