FastY1[b1]

Y1[b1] /. HB[1] -> 1

t1=Y2[BR[Knot[3,1]]]

Timing[t2=FastY2[BR[Knot[3,1]]]]

Timing[t3=FastY2[BR[Knot[4,1]]]]

Timing[t3=FastY2[BR[Knot[4,1]]]]

Timing[t4=FastY2[BR[Knot[6,1]]]]

Timing[t6=FastY2[BR[Knot["K11n34"]]]]

Timing[t1=FastY2[BR[Knot[8,17]]]]

Timing[t2=FastY2[BR[Knot[8,17]] /. l_List :> Reverse[l]]]

t1-t2