Miriam Blackbart @Maddyb

Well what makes prims/sculpts "laggy" to other's is how many polygons they have. In order to make a cube deform nicely you add extra polys to it. A mesh object in theory doesn't need to worry about this limitation as much since if your making a box you've probably intended it to stay as just that, a box. As such you'd only need the poly's necessary to do that one purpose and that's it. So a prim has like 54 polys to accommodate the cut/twist/etc functions where as a mesh box might only have 6 polys one for each side.
That said most people model for SL (and by extension opensim) as if they're planning on doing a single frame render and not put those models in a game so the poly count on some of this stuff is INSANELY high thus defeating that advantage to mesh really.
Most mesh bodies are MUCH more high poly then necessary so they are definitely lagger for other's viewing them as apposed to the system body which only has like 7k poly's. Compare that to Athena/Maitreya's 100K.
This is all speaking from the perspective of the end user's computer loading it all. Here I use lag to mean framerate drops which is the usual result of loading all those polygons. I can't speak to what this all does to a server however.

Apparently this place considers a women who is 5 foot 4 a "child" since I got teleported home. lol ok.