New Serial DOPAIR2

When we work out last_pj in DOPAIR2:

969 int last_pj = count_j - 1;
970 while (sort_j[last_pj].d > di && last_pj > 0) last_pj--;

is it not quicker to start from 0 and move outwards instead starting at the edge and working our way in? e.g.

int last_pj = 0;
while (sort_j[last_pj].d < di && last_pj < count_j) last_pj++;

The same applies for first_pi.