To make an analogy: If one yoctosecond was equivalent to the size of a human cell, one second would be the size of the milky way (in meters that is 1e-3 vs 1e21)
If there was a computer that performed one operation per nanosecond and it would take 100 years to do a particular problem, then that same problem would be solved in approximately 3 microseconds on a machine that could perform the operation every yoctosecond.