A narrow kerf chain/bar on a small saw allows an underpowered engine to perform better... in small wood. As the wood gets bigger, high chain speed doesn't mean faster cutting speeds because the need to clear the chips out of the kerf is much higher... and for this you need a wider kerf chain. The .325 chain is a nice, intermediate compromise for saws around 50cc and this is the reason Stihl uses it on saws like the MS-261 but goes with 3/8" chain after that.
I'm not sure what performance gains you expect, but I can tell you that a bigger saw running narrow kerf chains/bars will eat through chains a lot faster. If you look at the chains, the reason is obvious... a lot less metal. Cutting bigger wood means the chain is buried in heavy, dense wood for longer periods of time, trying to get through harder, tighter knots and all manner of things that end up inside trees. The lighter chains don't hold up to that abuse as well as the beefier, larger sizes and dull faster, wear out faster and ultimately piss you off faster.