Will Segwit embedded inside P2SH save fee compared to P2PKH?
Spending a P2PKH output in an input of a transaction requires 4 * (36 + 1 + 1 + 33 + 1 + 72 + 4) = 592 weight units. Spending a P2SH-P2WPKH in an input of a transaction requires 4 * (36 + 1 + 1 + 22 + 4) + 1 + 33 + 1 + 72 = 363 weight units. Thus, given the same fee rate in BTC per weight unit, it will be cheaper to spend from a P2SH-P2WPKH output than it is to spend from a P2PKH output.




  He said less efficient. I want to know how much? Transaction size will be smaller than normal...?


P2SH-P2WPKH (P2SH nested segwit) is not less efficient than P2PKH (non-segwit). It is less efficient than P2WPKH (native segwit).