Only to inform... Lee's sub is fastest, but on BricsCAD...
Here is my testing result of (extremum) vs ((car (vl-sort)) :
: TEST
Elapsed time for (extremum) : 15 milliseconds...
Elapsed time for (car (vl-sort)) : 171 milliseconds...
Thanks all for participating...
And BTW. If someone would need 2-10 times faster without changing LISP, he/she should just use BricsCAD... For me it worked well on 1 example (32 - depth, 50 solutions, 2 points per (processpt)), but on another one (32 - depth, 100 - solutions, 4 points per (processpt)) it crashed around (unique) - there was probably needed (gc) call while recursing...