The current single driver build of Mame is a bloated 92MB. Mess-0.134 is 16MB.
You're probably comparing a stripped release build with a full debug build. It's a common mistake. But it's also worth noting that the size on disk of an executable doesn't predict either the runtime RAM usage or the execution speed.
I didn't know about the requirement to email an admin (not exactly obvious)
The requirement is listed in red letters and a large font when you try to register. For some reason, people miss it all the time anyway. We might have to make the instructions spoken or something.