Dose the sparsity affect the the iterations and velocity ?

[qbsong]

I was use the sparse matrix library to speed up my calculation in solving the equation of AX=B.
But I found a very confusing question that is the iteration times are too large to slow down the whole calculation velocity . My sparsity is about 10% . Is it the reason why my iteration times are
so large ? if you kown the reason please send me a reply .Thank you very much.