scientifically smoking supplies nicotin which is a stimulant but has long term effects if refer to michael tal .
if smoking makes you feel better while playing then smoke at your own risk though better alternative is coffee which is more healthy and common option which is recommended at tournament halls while smoking is band .
back to topic smoking doesnt provide any extra processing power in chess , only a stimulant and stress reliever , cancerous on the long run if i may add
Harry Pillsbury was a chain smoker