Three problems --- Graph coloring, Stable set, and Clique --- are known NP-hard problems (on general graphs) that can be solved in polynomial time, when we know that the given graph is a perfect graph.
Are there other NP-hard problems (on general graphs) which are either known to be poly-time solvable on perfect graphs or known to be NP-hard even when restricted to perfect graphs?
For example, is the problem of deciding the presence of a Hamiltonian cycle in a perfect graph poly-time solvable or is it NP-hard, when restricted to perfect graphs?