I thought I'd up the max brickcount to 1 million. It was all going good till I got past the limit, 256000. The moment it got past 256000 all bricks I placed were invisible and my ghost brick disappeared. I timed out and reconnected. When I connected I couldn't see any particles. My ghost brick was invisible and all bricks I placed were invisible.
I thought that the brickcount could be overridden by entering $Pref::Server::BrickLimit = "256000"; into console. It worked for the most part but everything was jacked up past 256000.
All the way up till 256000 I didn't get any FPS lag at all. I wonder what the engine could really handle.