"How many they are is irrelevant. I will see them fall."

Every. Last. One. His hatred toward the Jedi may have faded some with time and if the Emperor lied to him about killing Padmé and his son, then what else had he lied about.

Still, that doesn't mean he will fail to follow his masters command. Not without a very compelling reason.

"Perhaps you feel that you are incapable of facing them? Quiet your doubts, it is only a matter of time before you will be strong enough."