If you believe the stats at Ballistics by the Inch, +P loads will give you a 100 foot pounds of energy advantage and as much as 250 higher muzzle velocity from a 3 inch barrel as opposed to standard pressure rounds.

If you believe Lucky Gunner results, the Federal HST 124 grain standard pressure and the +P round have the same velocity and energy from a 3.5” barrel, with the penetration advantage median depth going to the standard pressure round.