It certainly slows the framerate. About 1 per second at launch on my underpowered laptop DX. I have seen your Pepperpot design, I started off with something similar and added another layer to it. When I got bored of that, I decided to add yet another layer. It took me a while, the VAB gets very slow and my mousepad doesen\'t help. I\'m also something of a perfectionist, trying to get all the tanks at the same level, down to the same pixel. I\'m not entirely happy with it, I think some of them are out, but I didn\'t feel like going to all the trouble. I have many versions; 7 tanks like your Pepperpot, 19 tanks (add another layer), 37 tanks like this one. I have another where I started with a 19 tank base and added two tanks to each module, giving three tanks per module. I then added winglets to the middle stages of this and tried a few mun landings. One trick I like to do with the modular 4 is to max it vertically til 70km, then turn 90 degrees until the apoapsis reaches munar orbit shut the engines off, and you will get caught by the mun . It\'s a quick way to get there. I have an 'rcs return' version of the 'modular 4', used to test returning from the mun rcs style. Any changes to the last stage deletes a few fuel lines, though, and it takes ages to re-plumb all the layers correctly. I\'m slowly working on a 4 or 5 tank per module version of the modular 4, that should have a massive delta-V capability Takes ages, would be cool if someone could make it for me. Daisychain fuel system sounds good, I think I\'ll use that from now on