There's no rule that the SD-8516 has to run at 1.28 MIPS, but, it's a nice standard that should work everywhere. Maybe later we can increase it – but, do we even need to?
In a standard number shuffling test featuring LET, some math and an IF, the system will pull over 3,000 lines of basic per second. Of course, this is using the fast integer A-Z system.
In a for-next loop, the system can draw 300 random pixels of random color per second, or, 100 random lines.