Like i indicated on the other threads you started and/or commented on this topic, it's a chronic problem as of late. It's not about mail processing, it's about Customs inspection. Google the search term 'Chinese Mail Fentanyl' and you'll see the cause.
Lettermail from China now has to be inspected by incoming Canadian Customs for toxic illicit drugs being smuggled into Canada by Chinese drug cookers. Fentanyl is killing Canadian habitual and recreational drug users in record numbers. Two grains the size of table salt granules is enough to kill people and it's making its way into even street pot. First responders run the risk of dying when they are accidentally exposed to it while answering crisis calls.
It's a major, major problem that supersedes the inconvenience of online shopping package delivery delays. I would suggest that until this problem is fixed, you shop from sellers in North America. You mentioned you're a drop-shipper? You will want to workaround shipping to Canada from China, or instruct your suppliers to do something about it.
Here's two articles to get you started. You don't even have to research them yourself, just read.
http://www.theglobeandmail.com/news/national/how-fentanyl-is-getting-through-canadas-border/article2...
And a piece in greater detail:
http://www.theglobeandmail.com/news/investigations/a-killer-high-how-canada-got-addicted-tofentanyl/...
