Monday, October 16, 2006

What's all of this about framerates anyway?

The single most discussed topic regarding performance of Flight Simulator has to be FPS (Frames per Second) or framerates. Exactly how this all works has been a bit of a controversial topic, especially with the new version because it is so resource hungry. Well, ACES is to the rescue with their first featured article.

There's much more to what makes up framerate performance that the number itself. Something that most do not realize - framerate performance should be measured only when the sim is in a paused state. To determine how a setting change has affected FPS, it is best to pick a single location at around 1000 feet AGL. The area between KSEA and KBFI has been a good benchmark area for me. Panning around the aircraft while in pause gives a good representation of the performance you should expect.

In the article, ACES explain that it is not only the framerate itself that makes FS fluid, but also avoiding what they call volatility, or, better known to the on-line community, the dreaded "stutters." I found a tip by an ACES dev on the AVSIM forums that gives us a way to improve volatility that is worth repeating here:


If you're getting stutters/"pops" during turns or when pan your view around, try adding this to your fsx.cfg (located in yourprofile\Application Data\Microsoft\FSX):

[BufferPools]
PoolSize=5000000

The default pool size is 1 million but sometimes (If a lot of things are drawing like autogen) that isn't enough. Increasing it to 5 or even 10 million trades off some of your video memory against having to re-allocate these things all the time.


-Brian @ Aces

Of course exactly what size the PoolSize should be increased should be tailored to one's specific PC, and experimented with. If you take away too much from the video card's buffer, then other areas of the simulation will suffer.

They explain how FSX analyzes your PC upon installation and determines the best settings for optimum performance. Certainly users are free to experiment, but the state that is first implemented should be the benchmark. ACES also emphasize the importance of striking a balance to gain a satisfactory sim experience. If the simulation experience is not to your satisfaction, experimentation is the answer. I also suggest creating setting profiles based on the type of flying you will be doing. For example, if you are planning to do an IFR flight, it may be beneficial to turn off all of the AutoGen, since your attention would be centered inside the cockpit. We have Mike Gilbert a.k.a. tdragger to thank for that added config saving feature.

1 comment:

Bruce said...

I have noticed that on my system FSX displays a lower frame rate than ATI Tray Tools. In FS9 the frame rate is close to the frame rate displayed by ATI Tray Tools. I have two images that show what I'm talking about. If others experience is the same then their FSX frame rate is not as low as they think it is.

http://bruceatkinson.com/images/fs9_fps.jpg
http://bruceatkinson.com/images/fsx_fps.jpg

Bruce