It's already very fast, but you can improve it somewhat by doing your rotations with 

$num = chop($num) . $num;



      Rate    s chop
s    258/s   -- -14%
chop 299/s  16%   --

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the lowliest monk

In reply to Re^4: Rotationally Prime Numbers Revisited by tlm
in thread Rotationally Prime Numbers Revisited by Limbic~Region

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