Why Secondlife use always 100% oor 50% of the cpu? (please sticky)

Second life is a 3D real time application, it's use of the cpu seems to puzzle a lot of peoples new to SL.

Why SL use cpu even when i am doing nothing?

Because SL is a 3D real time application it has always something to do, most of it's time is used to generate images for your display, so even if you do nothing SL must refresh the display to reflect the changes in world that are happening all the time.

Why on some systems it use 50% and on some 100% ?

Some high end computers have what we call dual core processor which are basically two independent processors on the same chip. Second life is what we call a "single thread" application and because of this cannot "split" itself on both of the cpu, so instead it use only one of the two.

couldn't SL use less CPU time ?

Not really, what is doing SL is basically fighting for resources system, usually when you have a very powerful computer you feel the game smoother than on a low end computer, it is because on one of the computer, SL has been able to draw , lets say 60 times the screen in one second (very smooth, the illusion of fluid movement is somewhere 24 refresh per second) while on the low end computer it was only able to draw a pity full 5 images per second.
But your mileage may vary depending of your settings in SL.

Wouldn't a frame limiter reduce the CPU use?

It would probably only on very high end machines, which is where it would be the less interesting. (Especially since most high end machines are dual cores now)

>> Some high end computers have what we call dual core processor which are basically two independent processors on the same chip. Second life is what we call a "single thread" application and because of this cannot "split" itself on both of the cpu, so instead it use only one of the two. <<

I think this bit of information is outdated. The 1.15.1 distributes itself nicely over both processors on my dual core and setting affinity to just one does not make a difference in FPS (this seems to have been a problem with earler versions).

Yes please sticky this, its very common question , and has nothing to do with jerkyness/fps slowdown wich most associate with Secondlife high cpu use , high % does not make it laggy in SL, it just reserves cpu but doesnt actually do anything till it renders.