Instances run on a shorter refresh cycle and can be more sensitive to lag spikes compared to the open world. So there could be a routing issue in play. Being overseas you are a likely dealing with more latency than most in North America if you are on the NA/EU servers in Canada. May be worth trying some free trials on VPN services to see if it clears things up any. If so, then it is very likely an issue occurring along the route your ISP is assigning you.

It should be noted that both Verizon and BT customers have been reporting a lot of quality of service issues recently...and not all tied to this game. So if you are using their lines at all (either as your ISP or you get routed through them along the way), they could be part of your problem.