My cat snores very heavily & when i play with him with a feather toy for about 10 minutes he pants. why?

My cat snores very heavily & when i play with him with a feather toy for about 10 minutes he pants a lot. why? I found him outside of my apartment when he was about 9 months old. I had him neutered and got him his shots. He seems perfectly happy and healthy. He is laying in my lap right now sleeping. His breathing seems obstructed though.... he is about a year and much smaller than my parents cats...so maybe he was the runt and has breathing problems he was born with? What's wrong?