Mike,
I didn't spend a lot of time analyzing your model primarily because it seemed to really bog down my machine and did not look like an actual part but rather something you were experimenting with.
A couple of quick things I did notice. A triangle is a 2D planar object so do as a 2D sketch. Always go for the simple solution.
When you thicken a surface that is not planar the edges are not planar so a sweep of the triangle is probably not going to give you the geometry you want. I would do a Loft using the two edges as rails.
Whenever I run into a part that seems to really slow down I start trying diffferent methods to achieve the same geometry without the slowdown.
You might check out these parts, particularly the Seat. Some of the parts I modeled at least a half a dozen ways - not because my first attempt didn't work but because I was not satisfied that I had found the mose efficient method.
http://home.pct.edu/~jmather/SpyGadget/HammerHead_Mather.zip
Some of the parts I would do over if I had the time. You can probably tell which ones.
Also if you are just experimenting to see what kind of complex geoemtry you can create you might want to go through these tutorials first
http://home.pct.edu/~jmather/content/DSG322/inventor_surface_tutorials.htm
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