"If I recall correctly, over 90% of the Coptics were slaughtered by the Muslims when they first invaded Egypt, and the other 10% haven't been treated much better. "
Actually they left them unmolested for several hundred years, because the only wife of Mohammed to give him a child was Egyptian (Coptic), and Mohammed left specific instructions to be nice to them. Later on though some were killed if they couldn't pay their dhimmi taxes.
It appears I did not recall correctly.
I'm not sure where that false little factoid came from, but over the years all sorts of nonsense can creep into my noggin. I suspect my hearing that predates the Internet, hence it was not corroborated as it would have been had I seen it online.
I looked into it, and have a clearer picture of the Muslim invasion of Egypt, based on Coptic sources no less.
Thanks for the correction!