Saves them all, no matter what.

Without an external program like VBIS for Proton, there's no way to know which system variables are being used by a particular Handler.

But from what I've seen, while optimizing out what isn't used does increase the maximum interrupt frequency available, it only really helps if you're pushing the limits. For normal everyday interrupts (with Basic Language) the extra saves don't have that much effect, and helps provide stability.

And as always, if you really need the speed ?
The interrupts should be in ASM anyways. (no PBP system variables saved at all)

Which is one of the best parts of DT_INTs.
You can have both ASM and Basic Language interrupts in the same program.
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