Ik how, its just that my FPS are always jumping in other servers. At Winks CityRPG I would get 27FPS in some areas where I shouldnt. At Pecon7's I get about 90FPS. Then when I load Badspots Block Party I get around 20-30. I have a GTX 550TI, it can run everyhing I throw at it but with v21 im thinking of picking up a gtx 570 (not only for blockland).
It has to do with brick density, and how rendering bricks isn't as efficient as it could be. The fact that maps are created using bricks instead of more contemporary methods like plain models (like in Unreal Engine) or map brushes (like in id Tech engines and derivatives like Source and the Call of Duty games) means that it's difficult to determine what to cull, or not draw. In other words, when you look at a large build, a lot of bricks faces (or sides) are drawn when they'll never even be seen by the player.
Another method to reduce work for the GPU (this decreasing draw times, thus increasing framerate) is something called Level of Detail. The farther away the camera (and thus player) is from a given model, the less complex the game model is drawn, while still keeping a reasonable facsimile of the original model. This means that far-away models are less detailed (and faster to draw), but that detail would've been lost anyway due to the small size of the object, due to it being far away. Implementing Level of Detail in Blockland would be very difficult, if not impossible, for two reasons: 1) bricks are already very simple to draw (being mostly cubes or simple curves), and 2) constructing a good Level of Detail algorithm to combine multiple bricks into one model would be an enormously difficult task.
One solution that could be implemented is
occlusion culling. Blockland already does this to a certain extent (sides of bricks that are adjacent to other bricks aren't rendered unless a part of that side is "open" to the air), but a lot of bricks still get rendered that aren't even visible to the player.