Stilt is a magician in getting peak performance per watt out of everything. Down to tweaking individual straps for memory timing on binary firmwares for amd graphics cards.
3.6 @65W is impressive, almost stock speed at nearly half tdp.
Basically a 10% performance penalty for a 45% power savings. And you might not even see that 10% performance penalty if you're machine is bottlenecked on memory/storage.
It looks something like this: 4GHz 120W, 3.8 90W, 3.6 65W, 3.4 50W, 32 42W, 3.0 33W, 2.0 13W. This excludes the SOC.