Ported barrels direct gas up and out of the slide to aid in reducing muzzle flip. This can equate to faster follow up shots, or dot tracking during recoil on an MRDS equipped slide.
Note that by bleeding out some of the gasses, you are effectively robbing your slide of some energy. This can cause failure to eject and or stovepipe malfunctions. This is more prevalent with weaker ammunition. A lighter recoil spring and un-captured guide rod can be added to combat this. Do your research on the pros and cons of this. We suggest you run quality factory ammo to ensure reliability.