I've noticed that as well, last time my posterous was linked to on HN several people in #startups noted that it was quite slow.

At a guess if Sachin's not seeing it, it may be down to the TCP config on the fronting server, if it's badly setup it can vastly increase the number of network roundtrip data takes to be sent, so people on more remote networks (i.e in Europe/Asia) may well see significantly slower times.