I have experimented quite a lot with addon scenery and addon mesh. I feel that the addon meshes add a lot to the Sim - and at not much of a cost(performance wise).However, I have always felt that this is not the case for addon airport scenery. Most that I have tried are framerate unfriendly -- and cause pauses. The worst effect of this is when you are landing at an addon scenery airport. Just when you are concentrating most during the flight-- cough, stutter, pause. I have a machine that seems to handle most things in the Sim OK -- but addon scenery , no.Occasionally I have found a piece of scenery designed in Gmax that seems to have little impact on performance -- but it may be that other scenery design programmes may be the problem.Any thoughts?Barry

GMAX seems to be capable of producing sceneries with good performance providing the polygon count is kept reasonably low. There are tricks - that certainly are no secret to scenery designers - such as deleting surfaces of objects that are not visible such as the bottoms of buildings and internal polygons. Also some scenery designers use LOD (level of detail) modeling which displays increasing amount of detail (Polygons) the closer you get to reduce the demand on the processor at farther distances. Some designers are very good at making detailed sceneries of large airports that have little impact on performance. An example I can think of is the Fly Tampa airports.Another factor are the bitmaps used. I've discovered that images in 8-bit or DXT1 format are easier on the video card than higher resolution images. Also using smaller bitmaps like 256x256 or 512x512 is preferable. I've tried larger, higher resolution textures and had stutters as the video card struggles to load them.There are obviously techniques that more seasoned scenery designers, unlike myself, are aware of that allow them to produce highly detailed sceneries with low demand on the computer. Just wish I knew some of them LOL.There's nothing you can do about the complexity of the scenery in terms of how it is modeled unless the designer built in varying degrees of detail in which case you have to set you scenery setting lower. Sometimes sceneries will have static aircraft and other objects that you might be able to remove by deleting certain bgl's, again if you can identify which bgl's they are. I know of at least one guy who converted all the bitmaps in the texture folder, with imagetool, from 8-bit to DXT1 and he managed to eliminate the stutters that plagued his computer.Just some ideas, certainly nothing revolutionary. Hope this helps. :)Adam