Chainsaws

I just bought a 562 XP auto tune with a 28" bar (std Husqvarna bar and chain from dealer) It's first job was to cut rounds on a 28" diameter Douglas Fir. It took every bit of the 28" bar. When the dogs caught and bit in the chain would bog down and stop. I had to lift and relieve it for it to go again. Is a 28" bar just too much for this saw? Or is this a tuning issue? First time using, first tank of gas... filed with Husqvarna pre mixed high octane fuel. If I need to upgrade to a 576 to run a 28" bar that will really work when needed I will. Need real world advice.
Thank You!
Ryan