Homepage updater fixes

Reticketed from #1605 per [IRC](https://botbot.me/freenode/gittip/msg/7111004/).

EDIT: Local benchmark for the last commit (old vs. new), ref #1618:
````
$ ab -c1 -n100 http://localhost:8537/ | grep '(mean)'
Requests per second:    5.68 [#/sec] (mean)
Time per request:       176.016 [ms] (mean)
$ ab -c1 -n100 http://localhost:8537/ | grep '(mean)'
Requests per second:    30.80 [#/sec] (mean)
Time per request:       32.463 [ms] (mean)
````
Addresses also #1598, #1601.