The key thing to look at is not performance, but heat. How effectively can it cool itself?
Desktop towers normally don't have this problem at all, but laptops and mini computers usually do. They're designed to load something quickly, and then sit and do nothing but cool off while the user looks at it. Live video production doesn't allow it that time to rest, and so the heat just builds up until it has to throttle back (slow down) to protect itself. Then everything falls apart.
