I was able to reduce the reflection flicker some. The actual sun in the sky still flickers quite a bit, though I tried to reduce that too. Part of the problem is the original design of the "sun flares" and "overflow" features they used are put in a loop that doesn't always execute every loop iteration because if they execute every time, they greatly reduce the framerate. So I think they decided they wanted the features to provide some dynamic effect of the sun rays and those "rainbow" type flares, but tried to reduce the impact of the performance hit they cause. I do not intend to rewrite the whole thing, but I did try some changes to reduce the problem. Update the newest Maelstrom engine from today's update and see if it helps.
The foliage does cause some performance problems and they did provide an option to reduce the impact. Under Options, there are checkboxes to change the Foliage Quality. You can choose None, Low, Medium and High; the higher quality means more of them draw and can cause framerate drop, while Low will draw fewer of them. I do not know enough DirectX to improve the graphical calculations and shading programs to allow higher quality without an FPS drop, so the options to simply reduce the amount of foliage, or remove it with None are the only options right now.