Previous benchmarks tout great benefits, ranging from making pages load 2x faster to making mobile sites 23% faster using SPDY and HTTPS than over clear HTTP. However, when testing real world sites I did not see any such gains. In fact, my tests showed SPDY is only marginally faster than HTTPS and is slower than HTTP.
Why? Simply put, SPDY makes HTTP better, but for most websites, HTTP is not the bottleneck.
If you’re a website owner, the first thing you should do is adjust your expectations. Switching your site to SPDY will move you forward, but it will not make your site much faster. To get the most out of SPDY, you should work to reduce the number of domains on your page, and to address other front-end bottlenecks. Doing so is a good move anyway, so you wouldn’t be wasting your time.