You have to stand in line at the US post office, and it is a sloooww moving line.
You have to fill in a 'bed sheet' customs form with such niceties as the HS tariff number and the EEL/PFC, not to mention the complete name, address, business name of the sender the complete name, address, business name, postal code, province of the receiver, the detailed description of contents along with the value of each item, its net weight and the gross weight of the total package.
The clerk then has to re-type all this data into his computer while you stand there - thus assuring that it is a sloooww moving line.
The cost for shipping a $95 enlarging meter can be $35 - and the post office claims it looses money.
The package gets out of the country fast enough - but then it can sit in customs in Portugal (or Canada, for that matter) for 6 weeks.
The 6 week delay prompts lots of "Where is my xxx?" emails that have to be answered - politely.
Canada Customs usually takes mere minutes (at worst overnight) to clear items shipped from the US. Not sure when clearance ever took 6 weeks. Besides, that's the buyer's headache.