I've been using FlyInside from its very beginning, and lately mostly with XP11, but a few months ago (around the time of 1.7) when I tried using it with FSX I noticed very frequent dips in the timewarp framerate a few frames under 90, while the FSX framerate was good (never below 40s, sometime even in the hundreds). Now today I thought I'd try again as I'm planning to go back to FSX to enjoy a bit of Firefigther X, but I'm bumping into the exact same issue with the latest beta version too.
At first I tried FSX on my old win 7 session (dual boot win 7 / 10) and the problem occurred, so I thought "ok, finally time to move on and to install FSX SE on win 10 from scratch)". So I spend my afternoon doing that, fresh first install of FSX SE on win 10, fresh install of FlyInside (latest beta), and unfortunately I still had the same issues with framerates around 120/86-90 during my test session. Those dips create stutters and make it unplayable for me.
Does that sounds familiar to anyone? Not sure where to get started to diagnose that. Note that I had none of these issues with XP10 and XP11 which are butter smooth with FlyInside.
That's on a HTC Vive, i7 3930K @ 4.4Ghz, 16 GB RAM, GTX 1080. SteamVR settings are on asynchronous timewarp - that's what works best with other games, but is this potentially the issue (note that it's not an issue with X-Plane though)?