Welcome to SOLIDWORKS forums Dennis.
I know I have around 64000 configurations of one screw due to having custom properties assigned (material and Finish)
That is a huge one and too much heavy file. If you put few of them in an assembly, the performance is going down for sure (not sure how you're using it).
Not sure if this is a SW limitation OR Excel's.So as you've already said, you need to export the data as several files and combine them. You may want to check with your VAR/Reseller about it.
You might also find this post helpful for your future reference.