If I understand correctly, the problem is that the hash created on the client side is used to create the encryption key before the server side hashes are applied. Only the master password uses the extra server side hashes.
I think you might have missed his point. The gist of it is that almost all modern software is at least 100x slower than it needs to be, for no good reason.
Conventional software practises result in unnecessarily complex code that takes much longer to write and to execute than needed. The problem is so endemic that there isn't really even a good programming language available that makes it easy to use the capabilities of computers.
Fortunately there are a few pioneers trying to improve things, constructively creating solutions such as JAI. Casey is fighting against the fact that not only are industry participants unaware of the problem, buy they actually fight to write bad code to ship bad software to customers because they believe that is the pinnacle.