The hosts were always in control after Andy Williams had given them a 24th-minute lead but perfectionist Di Canio felt his side could have done better.
"We had to suffer a bit in the first 20 minutes when nothing was happening but in the end we should have scored more than four, maybe as many as eight," he said.
"I think we need to be more nasty and ruthless because we had many more chances and four goals was not a reflection of the way we were on top for so long.
"The lads did their best I must admit, I would say 90% of what they did was positive, but sometimes we were too tippy-tappy.
"I should be happy with four goals and three points from a good home win but I am not completely satisfied. We dominated everything and put them into trouble but we have to learn to kill off opponents."