The guy seems to know what he's talking about, and has actually run some tests but the test setup seems kind of weird.
Effectively he's saying "if you only change HTTP to SPDY and make no other changes, then it's 3% slower (though more secure)" or "if you only change HTTPS to SPDY and make no other changes, then it's only 4% faster" assuming your site looks like some kind of average of the top 500 sites.
And his conclusion is much more positive than most of the 3rd party coverage of it:
"I believe SPDY is still awesome, and is a step in the right direction. This study and its conclusions do not mean we should stop working on SPDY, but rather that we should work on it more, and make it even faster."
Guy does know what's talking about but there are some limitations to his tests - which to be fair he's pretty open about in the post.
The biggest challenge is optimising for SPDY is different to optimising for HTTP and so many of the test sites may have behaviours that aren't optimal for SPDY.
In addition to Google, Facebook and Twitter are/have deploying SPDY so I think we can be sure it has benefits.
Yeah, another way of framing it is: even if you do not put the least effort into SPDY, you will benefit a little from security, if nothing else. Tuning incrementally will buy you further improvements.
I believe there was a flaw in his argument, and that was Facebook was using SPDY on the front end, but not on all the back end services, or external services Facebook uses...
I really, really wish this particular link would disappear from the net. It is a TERRIBLE test. It has been soundly refuted over, and over, and over again. Yet it recurs.
He used a non-caching proxy with SPDY, against distributed non-SPDY back-end resources. This is not how anyone in the world will actually use it, and his test is effectively akin to testing the speed of a sports car by having it drive behind a transport truck: The whole foundation of the test is nonsense to begin with.
Not as SPDY as you thought:
http://www.guypo.com/technical/not-as-spdy-as-you-thought/
The guy seems to know what he's talking about, and has actually run some tests but the test setup seems kind of weird.
Effectively he's saying "if you only change HTTP to SPDY and make no other changes, then it's 3% slower (though more secure)" or "if you only change HTTPS to SPDY and make no other changes, then it's only 4% faster" assuming your site looks like some kind of average of the top 500 sites.
And his conclusion is much more positive than most of the 3rd party coverage of it:
"I believe SPDY is still awesome, and is a step in the right direction. This study and its conclusions do not mean we should stop working on SPDY, but rather that we should work on it more, and make it even faster."