Bought a house with a water efficient toilet for my basement. However,
it has a very hard time flushing - anything of substance just won't go
down without multiple flushes.

Is this because the super efficient toilet sacrifices flush power? Is
it becausse the basement is so low that there's not enough drop out to
the sewage line? Is it because the line is partially clogged? Something
else?

Should I go out and buy a better toilet? Clean the line with a snake?
What?