Major Description
Erlang R16B03-1 has a bug where the optimization wasn't turned on correctly. As we build Erlang ourselves we should check whether we pass in the correct flags in order to make it build optimized.
A user in #couchdb-dev reported slowdowns of 20-25% compared to R14.
More info about is available on the Erlang mailing list [1].
[1]: http://erlang.org/pipermail/erlang-questions/2014-August/080355.html
PS: I made this an MB issue as I want to have it public as it might help other people. Another reason is that I received this from an Apache CouchDB community member. Being open FTW!