35~45fps with the graphics options that came with the demo, with ~15 AI cars on track, I just started the demo, choose 1080p and RACE...

The GPU usage on nVidia inspector is 100%

rF2 is really dx9 yes

see bottom text; http://rfactor.net/web/rf2/rf2features/

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Demo doesn't do any AA out of the box right? Hmm I think 35-45fps is too low with default settings, only a resolution change. What happens when you set AA? Same FPS?

https://hostr.co/file/x9q15ipcsY3w/rFsettings.png

https://hostr.co/file/WsduQmuDYOz2/rFsettings2.png

These are the original settings (that I got 35~45fps)

I changed the AA ingame to "Level 4" and tried same track, same AI, and got 21~27fps

840M is not exactly a top notch card so 25 FPS at 1980x1080 with some AA sounds OK to me, especially if the GPU reports to be fully loaded.

Sorry for bumping, but I still have performance issues on LFS...


I'm able to play GTA V with 50~70fps at 720p on the gt840m, but on LFS that get 60fps on any potato-PC, can't keep 60fps here...

By starting LFS using the right click, I can choose what GPU it'll use, so I startd two instances, one with the HD4400 (onboard) and one with GT840m, this is the result:


https://hostr.co/file/GcxjGoVNMngc/LFS.png


Believe it or not, the left instance (with 88fps) is the HD4400

The right one is the GT840m, with 50fps...

Having a game run twice on different GPUs simultaneously might not give you a really relevant results because of how the Optimus technology works.

It might be interesting to see if there is any difference in CPU usage with the game running on different GPUs.

Your situation is very strange. Running on a bit older notebook (i5-3210M 2,5GHz, 8GB RAM 800MHz, 2x NVIDIA GeForce GT650M 2GB in SLI) I have 320 FPS on open configuration Westhill... I'm running Windows 7 Professional x64 and I'm using a resolution of 1440x900. I had no problems with the switchable graphics, every game used my both GT650M's power.
It's also strange that there's no memory usage on your graphics card... I use some widgets to monitor my hardware, and my GPU Meter (AddGadgets.com) shows my current memory usage in real time - you could give it a try.
Also, make sure everything is in "High Performance" mode, even your battery power plan (doesn't matter if it's on AC power or not, just keep it on high perf. mode).