Why is it taking so long to cook pasta and potatos?

I think that pasta cooked as per instruction is cooked at a full boil in a very big pot whereas i cook mine at 1 heat setting below boil to stop it from boiling over .

So 11 minute pasta takes 16 minutes.

I also suspect that many companies that make 'instant' type meals give false cooking times to make it sound faster than it really will be .

Just like they give ridiculous serving sizes for their packets.

"Seems to take" not sure what that means.Its' actually "easy as pie".Start your kitchen timer (you do have one right?) when you've added the pasta to the boiling salted water.Follow cooking directions on the box for doneness desired,and its finished when the timer goes off.Potatoes are a different story,and that depends what kind of potatoes you want to make.

Scalloped potatoes can take quite a while in the oven if they have not been pre - cooked, but pasta, once put into boiling water shouldn't take longer than 10 - 12 minutes.

It could be your 'elevation'?

Altitude does make a difference, but 550ft should not be enough o make much difference, you would need to be a few thousand feet up to be significant. As others have said, you must time from when the water gets to the boil.

Dry pasta take ten minutes when the water boils. Potatoes might take an hour. Is the water boiling?

Pasta needs a rolling boil for the amount of cooking time. So if you are timing from the time you put the pasta in (and knocking down the boil) and don't push the pot to a rolling boil with more heat it could take longer than recommended. 

Bring the water to a Rolling Boil. Then add salt. Adding salt before boiling will extend the time the water needs to boil and will eventually pit the bottom of the pot. 

Your perception of time is skewed. Ever wonder why one minute is 60 seconds, but if you are microwaving something, that 60 seconds feels like 5 minutes? 

What texture are you looking for in those starches? I salt a pot of water to taste like ocean, bring it to a boil and drop in the pasta. For spaghetti or linguini, about 9 minutes gives me al dente. Bow ties and shells take about 11 minutes. But if you are expecting really soft pasta, it can take 4 or 5 minutes longer. Potatoes are less predictable. If you are coming from scratch, try boiling medium Russets skin-on for 15 minutes, chilling them the removing the skin and slicing them. They will still pick up the flavors of the dish but will be more tender and retain their substance (mouth feel).

Pasta: the water has to come to a boil BEFORE you put the pasta in.  Salt the water as it comes to a boil.  For al dente cook as directed, for softer cook 2 minute longer than al dente.