The only spec that's is not subject to interpretation is the software itself. Otherwise it all boils down to relationship between the customer and the developer: personal trust, etc. And, of course, this creates immense place for psychological games, which mostly are lose-lose kind of game.
It's slow just because it's hosted on quite low-end server, while we are in the early stages. Now we're profiling and optimizing out slow parts, as well as thinking about hosting upgrade/scaling on several servers.
Yes, Mac is not native in our team..