When to release pawn tension

Hey folks, I'm somewhat mystified by the concept of pawn tension and when it should be relieved. I played a game as black against Magnus (age 9) recently, and as you'll see below, the computer suggests lots of pawn trades between moves 4 and 10 that neither side made. 

I know that there's no one answer for when you should trade central pawns, but what sort of questions should I be asking myself when I'm trying to make that decision? I've read that trading pawns is generally advisable when you're ahead in development, because it opens up files for your major pieces, but here the sides were about equal in development (and sometimes Magnus was ahead), so that wasn't much help. Are their particular tactical or positional things I should be looking for? 

The in a nutshell answer to your question: "When do you release the pawn tension?"

When you gain some type of advantage.

I am 100% in favor of only playing moves that give me an advantage; the problem is that, as a beginner, I don't always know why a particular move is advantageous or what advantages I should even be looking for. So, in the game above, what advantages were Magnus and I overlooking when we kept the tension against the computer's recommendations? Was it about tempo? Open files?

Honestly, at your level pawn tension is not what you should be concentrating on for improvement.  That will some later.

In order to answer your question, you will need to give specific examples.

This is very helpful. These are exactly the sort of questions I'm looking for. Thanks for taking the time!

Glad to help, and hopefully someone better can add to this.

This video shows some good examples.

https://www.youtube.com/watch?v=c3B34oKM0oI&t=1s

I recommend watching the whole thing but if you don't have time then start at the 20 minute mark. That's the example I immediately thought of when I saw your question. 

I never even heard of the concept of pawn tension before this thread.

I subscribe to the strong/weak square philosophy.

i think in this particular case this trades help because it almost equalize for black as there will be columns for trades and position is almost simmetricall

This is my favourite example.  I did not truly understand the power of tension until seeing this video:

https://www.youtube.com/watch?v=EmJcUI_wSy8

It focuses on piece tension rather pawn tension, but the idea is the same.