This super intesting stack overflow answer explains why -in programming- if you have a sorted array, somehow magically it can seem like it’s easier to process each element vs processing the same array if it were unsorted.
tl;dr - branch prediction
With a sorted array, the condition data[c] >= 128 is first false for a streak of values, then becomes true for all later values. That’s easy to predict. With an unsorted array, you pay for the branching cost.