At YYZ, expect to remove shoes, laptop and partake in the liquids nonsense if flying to the US. FWIU, you do not need to take off shoes or remove laptops if flying domestically within Canada.

Many of the YYZ screeners are not native english speakers (which I've used to my advantage when they tried doing gate secondaries), but they are far less obnoxious than their TSA counterparts.

Because the 'line' is held up by US immigration/customs pre-clearance, there is generally little-to-no delay getting through the screening checkpoint itself.