Support 18 Wheel of Steel: Across America Visual/Performance Issue

I'm having some troubles that I don't know how to resolve.

If I have the GFX device of the game set to OpenGL, then I can't do anything because the game responds really slow and super laggy. For example, the signals/flashers clicking are, like, click... click... click... click instead of click, click, click, click. I can fix this by changing the GFX device to Direct3D8 which makes everything super responsive and not laggy. The problem is that then there are some visual issues, such as freeway signs or signs over trailers not displaying their text, though in the freeway signs' case, they'll start flickering for a very brief moment when I'm right by them and go under them. Other visual issues include the headlines not looking right and such.

Spoiler: OpenGL - Signs and Headlights

Spoiler: Direct3D8 - Signs and Headlights

Notice the lights look jaggedy and don't extend all the way to the building. When driving, the jaggedies will move like waves.

This wasn't an issue last time I played this, which was when I was on Windows 7 and on my now broken computer. I don't remember what GFX device was being used then, but I know the default is OpenGL.

I can post the graphics setting if needed, but I've tried playing around with those to no avail.

@Mixt, maybe this sounds like a less complicated issue than that previous big issue you helped me with?