S!
I have none of those issues except some VERY small stops now and then due texture loading or whatever. But I would recommend you to check a few things I list below and see if it helps
First of all in most cases Application Controlled is the best setting in the GPU control panel, forcing AA or AF can bring undesireable or no results at all. The in-game AA works from not at all to very little, so using it is kind of useless. For example the SMAA Injector gives far better results with less FPS hit, but the VAC thingy on Steam is not 100% sure so I would use it offline only.
Secondly make sure Epilepsy Filter is OFF aka not ticked in graphics settings. At the same time disable SSAO too and along with that check that you are running Full Screen ON in graphics. Using VSync or not is up to you, I use it ON.
Then to other game settings. Forest at Medium or Low gives some boost to FPS. Effects at Medium give nice boost with smallish hit on the effect quality, but I can live with it. Also set building detail to Low or Medium, but their amount to Unlimited. Then the more important thing, texture quality. On ORiginal it hogs a lot of memory and reduce performance, using High is a small compromise for better performance in game.
What has a big impact in game are the Shadows, they can cause quite a big FPS hit, but without them game is a bit dull though. If you are into conf.ini editing then changing the ShadowMap size from 5 to 4 can help some. Grass can cause some FPS loss and stuttering, really boils down to personal preference if want it or not..but you will not see it above 100-300ft anyway. Roads have some impact but nothing big.
Then a way to help performance, at least for AMD users, if not others too is to disable the UBI logo video logo.wmv. It can be found in the X:\Program Files(x86)\Steam\steamapps\common\IL-2 Sturmovik Cliffs Of Dover\core\parts\GUI\ Just delete or rename it.
Try these and others will for sure add some tips too