Just so everyone is on the same page I thought I would give some details on what I found on how stutters manifest themselves in MSFS.
The simple explanation is that stutters occur when MSFS experiences a significant drop in frame rates past a point at which it interferes with the smoothness of the display. I call this point the the stutter threshold.
You can see this if you are using the MSFS frame rate counter. Very conveniently this counter colours the various frame rates it is experiencing (as near as I can work out):-
. Green - above 60
. Yellow - between 30 and 60
. Red - between 15 and 30
. Purple - below 15
The information on this counter scrolls from right to left and the full width represents a history of just over a second. The numbers on the right only relate to the last vertical shaft of colour on the right.
Looking at this information while flying in MSFS I always see stutters always occuring when purple appears. Generally red appearing doesn’t cause a stutter unless is right down towards to cutover near purple at 15.
So no problem here, all green & yellow and MSFS runs smoothly.
Still no problem here - the red is still above the stutter threshold and smoothness reigns.
Once the frame rate drops below the stutter threshold, there appear to be 3 versions of stutters:-
. Micro stutter - a single drop below the stutter threshold. In this example the red didn’t cause a stutter, but the purple to the right of that did.
. Stutter - a couple of drops that occur together - These are more noticeable in MSFS than the micro stutter, and consequently more annoying.
. Sustained Stutter - a consistent frame rate drop below the stutter threshold.
Pauses - Now these are really tricky as they do not leave a trace of themselves in the frame rate display. The screen just freezes for ½ a second or so, and even the frame rate counter itself appears to freeze, leaving no trace.
Cures
. Micro stutters, stutters or pauses. I have not found anything that does much here. Optimising your graphics settings helps, but my testing and the general consensus is that this is an optimisation issue only Asobo can address.
. Sustained stutter - Item 46 in my list of cures seems to be the fix for this one.
The last thing I’ll mention here is what else is going on here when you look at the whole frame rate counter graphic. Remember the numbers on the right are not relevent to anything other than the last shaft of colour on the right.
Above you can see the the stutter in red was replicated in the MainThread and also a lesser extent the RdrThread and Manipulators graphs. But the same drops do not appear in the CoherantGTDraw or the GPU graphs (although this is not always the case).
Here is another example of where there was lots of red but no stutters (they hadn’t dropped enough to reach the stutter threshold). Not the clean green of both the RdrThread and Manipulators.
Lastly “why does all this happen?” Don’t ask me, I didn’t program MSFS. However it may be clue for those who did as to why this happens.