" ... like CygnusEd with its hand written assembler scrolling that remains, 30 years later, my benchmark for "fast and smooth enough" editor scrolling. Essentially nothing has yet matched it ..."

Here it is: https://www.youtube.com/watch?v=L41oIvre9K0

For those who never used CED on an Amiga, this is how it ran on now 30 years old hardware clocked at 8 MHz.