This is the feature I am talking about in Aspire/VCarve:
When you have this unchecked the toolpath “rolls” around the corner. When you check it you get a perfect 90 degree corner, no radii.
Most people should leave this unchecked by default unless you have a specific reason to turn it on.
A small radius speeds things up and makes the machine run smoother. A true hard corner and slow the machine down.
It should also be noted on EX control the “smoothing” settings can also have some effect on hard corners (depending on how you have smoothing setup)
This feature is not available on Mach