I'm sure this has been discussed, but why does FS9 hit the CPU so hard, at least so much harder than other games?A machine that gets high FPS playing FEAR or what have you, with colourful explosions, fancy effects, and highly detailed characters in 3D, bogs down when faced with a bunch of monocolour rectangular buildings on a clear day?What da dillio?(Not a complaint, a curiosity.)

Because FS is basically a math cruncher/simulator.Per seconds a lot of calculations/variables needs to be processed in order to determine the flying characteristics etc etc.The amount of these calculations are much much higher (and more complicated) then for example in a FPS.

In your average FPS, the "room" the PC has to calculate for is usually something not more than say a couple of hundred yards square and maybe a hundred feet high. Most of the times, much smaller. In flightsims the "room" is (depending on visibility) more like 30 miles square and 30,000 feet high. Thats a heck of a lot of data to maintain. THrow in some nice thick cumulus clouds, a bunch of AI traffic, and some autogen and you've got a veritable datastorm for the PC push around.

Hi1) It is 3D (though so are many other programs now), so all scenehas to be manipulated using 3D matrix calculations.2) The scene is "real", ie as noted by the previous post you havea long sight distance from you current point of view. All the pointsin the view are different and do not repeat as they are real and changeas function of the world terrain and land class. Ie, consider a program like IL2 which is also a flight sim - the scenery isnot so exact and so the scene objects just repeat - so there arenot many of them and all have the same matrix to plot - just withan offset to put them in different places. With FEAR, nothingis "real" so it can look like anything. 3) Users like it to look good ! To make something look good you haveto make the image more complex with more detail. The higher theresolution (quality of image) the more objects you must transform (see-1)4) Animation : Anything that moves which is not part of the currentflight process is animated. This includes clouds, landing gear,traffic (AI - or cars in FSX). All of these need to be "moved"all the time in 3D. You want them to look good, so they need tobe complex and have 3D (not just rendered in 2D). 5) Although bangs and effects look good and clever they are simpleto generate computationally - they can be done as "sprites" whichare essentially 2D representations stuck on top of the 3D view. Theycan even be just a couple of bit maps that are "played" and these arevery easy to render.6) Everyone wants the correct physics model for flight sim, thiscan either be "finite element analysis (X-plane), or parameterisedequations of motion (FS9). To solve these equations - to integrateas a function of time - to represent forces and motion on the planeis difficult - really difficult - hard maths as computer code. Theseneed to be solved fast (ie fps rate). This is massively more complexthan bangs or texture mapped images of people walking/running orshooting people. 7) You have an elevated point of view, so you can see more, thingsmore in 3D, not just along the ground (in 2D). 8) Users just want more and more, they want better resolution groundscenery, they want building, trees, moving cars, every dial and switchin the plane to work, water effects (ouch), 3D clouds that neverrepeat (ouch), reflections (really ouch), shadows (ouch), movingfans in the jet, the entire world to 10 meter terrain, every airportrendered correctly, lighting models, smoke/water effects, passengers,etc......OK.... this is state of the art software, I've published scientificarticles on algorithms/graphics - but I still look and the viewand go wow. RegardsTom

part old and obsolete code, part size of the world rendered.