How so? By making the controls (all of them) tight enough that they require a deliberate motion to operate, even under stress/adrenaline dump of a defensive situation. Examples:
-Huge-button loose mag catch is great for competition. It can be easily manipulated at high speed, reliably, since it is easy to press. In a carry gun, it is more important that the all important first mag stays in place, and is not released accidentally as a result of either an imperfect grip on the pistol, or bumping around in the holster where it is located all day. You want a lower profile, harder to press button in a carry gun than you do a race gun.
-Trigger weight: light triggers are great for speed in the right hands. Not so much in a carry gun; the trigger should be heavy enough that placing your finger on it in a high stress situation should not be enough to fire the weapon. Most mfg seem to think this is about 6+ lb; and I tend to agree. Each shot in a defensive shooting should be deliberate and accounted for. I've seen several times in competition, people's tuned super light triggers AD'd... safely down range, but a round going down range when you don't intend for it to do so doesn't hurt anyone in a match, but it can and does in the real world... there is video out there on youtube to prove it. If a trigger is light enough to accidently press in competition, it is way to light for carry in my opinion, when you will be in a much higher adrenaline dump situation if you ever have to use it, and be subject to the resultant reduced control of fine motor skills.
Recoil spring: Often lightened for competition. You don't want to carry powderpuff loads.
Slide catch: Lots of people put a bigger one on to make it easier to manipulate in competition. Lots of people also ride them, which keeps them from operating correctly. It is another case of optimzed for speed vs optimized for reliability.
Speed (competition) vs. reliability (carry) is the general theme.