I'll try to answer that, and see if this makes any sense.
There are two kinds of performance when it comes to knives. The first is the kind that can be attained through accurate and appropriate heat treatment. Manufacturers have this ability, and many custom makers do not have the equipment to rival the equipment in industry for accuracy and repeatability. Of course, I'd say I do, but who wouldn't claim that? But seriously, I do.
The second, and the thing that has far more to do with performance is what custom makers do best. And that is the "compromises." Yeah, I know that the HK slogan is "In a world of compromise, some don't." That sounds great, but it just ain't true. Everything's a compromise, and you're kidding yourself if you don't believe that. Since you can't make a knife that will thinly slice a tomato and chop a cinderblock in half, any more than you can make a truck that will haul 10,000 lbs and still get 50 mpg, then the makers and the manufacturers have to decide where they want to come down on that spectrum. For every job, there is a tool that will do that job best. Knives can be made to be very task-specific, or they can be a jack-of-all-trades, though master of none. That is where a good custom maker can tailor a knife to suit a customer better than a manufacturer.
That's why it's so hard to compare performance between two knives, because one may be superior in one respect, while the other will be better in others. It is ultimately up to the buyer to determine what the real job of the knife will be and to buy the knife that will suit his needs the best. Most "combat" knives carried by active duty personnel, are used for cutting real things - not rocks or armor plating, so my military knives are cutting tools, first and foremost. That means I have traded off a measure of "indestructibility" for what I'd call real-world performance. You could hurt one of my blades if you really set out to try to. But you can damage your M16 if you use it as a prypar, and you can damage a HUMMVEE by not changing the oil.
Every tool has its limits, but if you understand where those limits are, and the care and maintenance required to keep it working at its best, then that tool will ultimately work far better than one that is marketed as a tool that can do anything and never require maintenance.