That's still 100 irrelevant units later than the server sent the update. This is like saying the first byte of the packet takes 100ms to arrive but the subsequent bytes in the packet are instant!

It's not quite right. You'll never have updates in microseconds even if your ping is, say, 7ms.

At best you can be ~2-4x as fast as long polling on HTTP/1 -- an order of magnitude is a ridiculous statement.