Up until March or April this year, AC could've blamed the government for delays at customs and immigration but it's mostly AC itself to blame since then. UA is able to operate flights to YYZ mostly on time with some delays while AC, especially Jazz has been habitually canceling half the flights and delaying the other half. In many cases, I had experienced no delays at either customs or immigration, the inbound aircraft arrives on time, and yet flight is still departs late due to lack of ground staff. I have also seen too many cases where AC is not able to turn around an aircraft in outstations within the scheduled turn around time and the delays compounds. The same flight is delayed for hours almost daily for weeks and there were no action to remedy the delays until recently. Jazz particularly has an atrocious cancelation record which I suspect due to not having enough crew members to staff the flights.