Talking amongst a number of combat vets, who are routinely training to hone those skills, in the capacity of professional soldiers and/or law enforcement, I will hear some say "slingshot", but it is a given amongst them, that this term does not describe the use of the thumb and finger to pull against the rear of the slide, like a slingshot. To eliminate confusion, you will now hear this poor technique of thumb and finger as being called slingshot, as that is what it mirrors, with the correct overhand technique being described as a power stroke, same as used to clear a malfunction.
Why the slingshot is bad and power stroke is good? Under stress, it is easy to ride the slide home w/ slingshot, not so w/ power stroke. The power stroke uses large muscle groups and gross motor skills. Such power stroke is also the same technique used to clear a malfunction.
Use of the slide lock is indeed a bit faster, but it does carry baggage in combat. It is a weaker technique requiring fine motor skills, and it is a completely different and added technique having no value at clearing a malfunction. Also, it does not maximize slide travel and spring power to aid placing the pistol into battery. Now, the trend is to save the slide lock for timed competition, while saving the power stroke for two way gun fights.
There are some exceptions, such as certain pistol designs can be placed on safe while the slide is quickly worked with a power stroke.
Me personally, I would only consider a combat pistol that could readily be power stroked, either 2-handed, or 1-handed off strong sights. Would not use extended slide lock as it adds risk of engagement with a high straight thumb combat grip.
Your life is on the line, so you're going with the slower method? This thinking makes zero sense to me. If my life is on the line speed is definitely needed!
