From: Eric Wong <normalperson@...>
Date: 2015-07-27T10:27:17+00:00
Subject: [ruby-core:70132] Re: [Ruby trunk - Bug #11396] [Open] Bad performance in ruby >= 2.2 for Hash with many symbol keys

Possible fix is to memoize hashval inside struct RSymbol:

http://80x24.org/spew/m/1437992270-20549-1-git-send-email-e@80x24.org.txt

Much better than before, but still slower than 2.1, I think.

Only lightly-tested, and on hardware which doesn't benefit from
power-of-two sizing anyways.  Sorry busy and don't have access to
better HW for benchmarking for a few days.