Prior to the introduction of mesh, every object in Second Life was made up of individual parts called primitives, or “prims”. The total number of prims making up an object is the prim count, or “land impact” of that object.
With mesh, builders can now upload complicated objects that don’t use prims, but each mesh object is still given a land impact based on its size and complexity.
Each region in Second Life is allowed a maximum land impact for all objects. For the main region of Inspiration Island, the maximum land impact is 30000, and for the second region (Inspiration Island Annex) the maximum is 20000. That may seem like a lot, but keep in mind that each of the regions has an area of 256×256 meters, and you can build up to a height of 4096 meters, so the total volume is around 268.5 million cubic meters per region, and you can put a LOT of objects in a space that large!
The main region of Inspiration Island is current using around 21000 of its allotted 30000 land impact limit. The more objects a region has, the more it contributes to “lag”, or the perception of things slowing down. There are other factors that can affect lag, but land impact is something that everyone should be aware of and do their part to control.