The AVSIM Software and Hardware Guide, pinned at the top of the FSX Forum is a good place to check out for the best settings.

I can't believe that I never saw this guide before. Just had a quick look and it looks excellent! Thank you.

Lastly, I made a few changes in my fsx.cfg following instructions from FSLabs forum but didn't have time to check if I finally reached my goal. If not, I will definitively follow your advice and reset this fsx.cfg.

For information, I installed the whole system following the tutorial from Nick on simforum and I didn't make much change to fsx.cfg before trying venetubo.

 

The only way to check this out for sure is to rename your FSX.cfg to FSX.orig then restart FSX. Make some basic modifications to your FSX settings, like monitor resolution, but try to keep your the settings under Scenery and Traffic at the default. Now see if you have an OOM message.

Thanks again Jim.

I should have done this before. I did follow your advice and got rid of this OOM problem. Now I need to rebuild my fsx.cfg. Do you have any advice on where to start? Should I go first in the GUI and adjust scenery, aircraft, traffic... settings or should I try first to set the tweaks like bufferpools, affinity mask...?

There's an AVSIM Software and Hardware guide pinned at the top of the FSX Forum which provides excellent tweaks and settings for your FSX.cfg as well as your display driver settings.  I would go there first.  The key to tweaking is to understand the tweak before you put it there.  Some of the tweaks, like the Bufferpool, do not work on every system and will in fact bring your system down if not set properly.  I don't use it and have great frames (away from payware airports and most of the time).  Display settings are important too as they can slow down your CPU if set too high and require too many resources.  The one "tweak" that is almost mandatory is not really a tweak at all - the highmemfix=1 fix in the Graphics section of your fsx.cfg.  This fix was suppose to be added with Acceleration/SP2 but I understand Microsoft forgot to add it.  Just take your time and be conservative.  I have found the less stress placed on your CPU/GPU, the faster the textures will render, the better quality of the graphics, and less stuttering.

 

Best regards,

Jim