SPDY makes HTTP requests go faster with several improvements:
The first, is request multiplexing. Rather than sending one request at a time over one TCP connection, SPDY can issue many requests simultaneously over a single TCP session and handle responses in any order, as soon as they're available.
Second, SPDY compresses both request and response headers. Headers are often nearly identical to each other across requests, generally contain lots of duplicated text, and can be quite large. This makes them an ideal candidate for compression.
Finally, SPDY introduces server push This can allow a server to push content that the client doesn't know it needs yet. Such content can range from additional assets like styles and images, to notifications about realtime events.