AppleInsider ran an experiment to test the effect of a T2 chip on video encoding. It found that a Mac Mini with a T2 chip encoded video in nearly half the time an iMac without one did.
Considering the possibility that the slow hard drive was the problem, we re-ran the test to both a USB 3.1 type C SSD on the iMac 4K with identical results. Additionally, running the test on an i7 Mac mini with an external 4200RPM laptop hard drive connected by USB 3.1 type A provided identical results with a higher speed encode, effectively eliminating the slow drive on the entry-level iMac 4K as a bottleneck. So, 100 percent of the difference between the iMac 4K and i3 Mac mini with the basic Video Toolkit is because of the T2.
Check It Out: T2 Chip Makes a Big Difference When Encoding Video