BSP vs Moveable Object performance question

NOTE: I am not a 3D modeler. As a result of the 1st statement I create a lot of things with BSP’s. If I leave them as BSP’s they render fine after I convert them, they usually have streaks or other types of artifacts in them. So this question is a little different. Which causes the larger performance hit, leaving them as brushes or setting them to moveable so the lighting isn’t baked in - though even that is not optimal). Is there a tutorial somewhere that shows what to do in Blender? I tried creating a small wall with one window and of course it renders just fine lol. I have made a complex stairway that renders fine, make a block and cut in a few windows and I usually have artifacts.
Thanks in advance…