Not as SPDY as You Thought
www.guypo.com/technical/not-as-spdy-as-you-thought
From the page
Saved with the link. Notes from 2007 to 2016 are mostly the page's own words, so this is probably an excerpt.
The results show SPDY, on average, is only about 4.5% faster than plain HTTPS, and is in fact about 3.4% slower than unencrypted HTTP. This means SPDY doesnt make a material difference for page load times, and more specifically does not offset the price of switching to SSL.