Yeees, no. Zip will replace the common tags (like "div") with a single "div" (in the compression dictionary), then a single character every time it appears (mo

Yeees, no. Zip will replace the common tags (like "div") with a single "div" (in the compression dictionary), then a single character every time it appears (more or less - it might be less than a single byte if it's a really common tag). So there'll be a wasted overhead of a dictionary of common tags (which is kind of wasted). It would be more efficient if both the browsers and compression algorithms could agree (beforehand) had a dictionary of common terms which would be likely to appear in the document. If you're compressing a lot of data which is likely to be similar, you can do this with a common dictionary. See - http://stackoverflow.com/questions/479218/how-to-compress-small-strings http://stackoverflow.com/questions/479218/how-to-compress-sm... Of course, my answer on Stackoverflow is pretty crude. You could create a dictionary used to compress the compression dictionary. Google is probably going to do this any time soon (if they haven't already) since they control the client (Chrome), server (google web server) and protocol (SPDY).