I was using FSX-SE and flying a smooth limited 25fps with refresh rate 50Hz at ½ refresh rate NVInspector with no alterations to the .cfg for months, then suddenly the stutters hit with a slide show of 16fps – WTF!!!. I couldn't find a reason for this maybe it was the full moon, maybe the FS Gods were displeased at my ineptitude.
So for the past couple of weekends I've been trying all the old tweaks I used when I had the boxed set. Buffer pools =no dice; highmemfix=sorry; affinity mask=forget it; FFTF=you must be joking; lowering settings=you get the picture. Now my system's no slouch i-7, GTX1080 48GB RAM etc, but FFS I should be getting better than this. I even decided that continuing to run FSX was flogging a dead horse, and that basically what my system was saying to me was “what the hell are you trying to make me do trying to run this ancient piece of crap”. So I uninstalled FSX resolving to just fly DCS & XP11 instead – only lasted until the next day when I thought I'd try a vanilla install as a last ditch attempt!! Did it make any difference to the slide show – did it heck!!!
Anyway, long story short, I fixed it, and I want to share my findings with the community as they're not something I've heard before on any of the forums. Of course, everyone's rig is different & I'm not suggesting this is any sort of magical tweak, but it worked for me.
Actually I stumbled on it by accident trying out different settings in scenery. FSX was set up as above (monitor refresh rate 50Hz at ½ refresh rate NVIns with no alterations to the .cfg), but with target frame rate set at unlimited, and it just so happened the frame rate I was achieving by altering the settings was averaging 25fps, which by pure coincidence was ½ the refresh rate. Everything was smooth as silk.
I also tried some things to bump up my frame rate off one of the forums. In properties tab of the FSX .exe I ticked 'disable full screen optimizations' then clicked 'Change high DPI settings' to switch 'scaling for apps' off. The frame rate shot up (especially in windowed fsx), but the stutters remained. After much tweaking it happened again – Monitor at 144HZ messing with different combinations in scenery etc with frame rate set at unlimited & ½ refresh rate NVInspector – when the settings reduced the FPS to around 70 the game started running as smooth as silk.
I just want to put this out there in case it helps some of you with stuttering. Its going to depend on your rig of course, but it may save some time for some of you suffering from the dreaded stutters like I was.