I'd been frustrated recently by poor framerates and stuttering. I should say that, for me, poor framerates = fewer than 10 fps. I went over in my head the changes I had made over the summer, and decided to change TERRAIN_MAX_VERTEX_LEVEL from 20 (38m) back to 19 (= 76m) in fs9.cfg. Sure enough, the mountains got more rounded (I've been flying in Holger Sandmann's Northern Cascades area) and the sim got noticeably more fluid. Still, I'm reluctant to let go of those well defined mountains. So what can I cut back on to get back up to 12 fps (which for me is quite workable)? One thing that came to mind right away is autogen, which is great in the cities but not so important in the mountains (especially in winter, when the trees are covered in snow anyway). Conversely, when you're flying around cities, the terrain is usually flattish if not exactly flat. (I realize there are exceptions: Innsbruck, for example, comes to mind -- but then I don't have 38m mesh for that area anyway). So, here's my new strategy: more autogen, less terrain detail for cities, less autogen, more terrain detail for mountainous areas. The question is how to implement this strategy. Autogen is easy enough to adjust from within the sim. But what about terrain detail? As far as I know, there are two ways to adjust this, with the slider and with TERRAIN_MAX_VERTEX_LEVEL. Obviously, it's easier and faster to work with the slider, since it doesn't require you to exit and restart the program. But are they the same? So here's my question: what is the relationship between the terrain detail slider and TERRAIN_MAX_VERTEX_LEVEL? If, for example, I halve my terrain detail (from 96 to 4, will that have the same effect as turning down my vertex level from 20 (= 38m) to 19 (= 78m)?

As far as I know, TERRAIN_MAX_VERTEX_LEVEL isn't accessible via s slider, or at least I should say there's no slider adjustment that can move it from 19 to 20 to 21.You don't mention your system specs, but I can tell you that even if you set TERRAIN_MAX_VERTEX_LEVEL to 19, mesh add-ons are asking MSFS to do more work and you may hit an fps "wall" no matter what. One thing you may wish to consider is to try an experiment with a lower screen res, such as 800x600x32 or 1024x768x32. Many have stated such a low res isn't very appealing, but I've found the extra fps offsets the slightly less clarity in the gauges. And of course, AI is another thing to scale back that can really improve fps.Other factors--lowering your cloud draw distance to 30nm and setting your vis (through weather) to match.-John