Any saw should be warmed up and broken in properly, maybe you did that...
STIHL saws tend to meet extremely stringent environmental regs, Zenoah (RedMax/Husqvarna) not necessarily so much. Husqvarna tends to have more power, STIHL less but the lower stress makes them last longer, Zenoah generally has both in older saws.
The MS311 is a Farm-and-Ranch saw, so not as light nor powerful as a Pro saw and more plastic inside means it can't put out more power without wearing out that much faster. For the price difference the Pro saws are a good investment, they will typically last longer and have better features. The MS261C-M has about as much power and a lot less weight, it's perhaps the saw you're looking for.