The demo is divided in the boot loader and demo 3 parts
The demo is intended to work with a 64K RAM (or more) PCjr. Booting from its own boot loader is needed to save precious memory. DOS alone takes ~20K of RAM. That is 30% of the total memory. You don’t want to waste that memory.
But how fast is an IBM PC 5150 compared to a PCjr ? or to a Tandy 1000? or how fast is the Tandy 1000 HX in fast mode (7.16Mhz) compared to the slow mode (4.77Mhz) ? Or how fast is a nop compared to a cwd ?
I created a test (perf.asm) that measures the performance of different opcodes and run it on different Intel 8088 machines. I run the test multiple times just to make sure the results were stable enough. All interrupts were disabled, except the Timer (of course). And on the PCjr the NMI is disabled as well.