Here are my results for the v2 binary.

I ran the v1 binary again, since the ambient temp now is 18 °C (21:20 local time) and the CPU fan didn't run so fast.

ktf_v1 (MD5: 7b2e91271a02ad9ed00666e8a69710fb):

-j1: Average time = 23.591 seconds (3 rounds), Encoding speed = 458.32x

-j2: Average time = 20.620 seconds (3 rounds), Encoding speed = 524.35x

-j3: Average time = 10.757 seconds (3 rounds), Encoding speed = 1005.08x

-j4: Average time = 7.783 seconds (3 rounds), Encoding speed = 1389.18x

-j5: Average time = 7.038 seconds (3 rounds), Encoding speed = 1536.23x

-j6: Average time = 6.827 seconds (3 rounds), Encoding speed = 1583.63x

-j7: Average time = 6.372 seconds (3 rounds), Encoding speed = 1696.89x

-j8: Average time = 6.763 seconds (3 rounds), Encoding speed = 1598.70x

-j9: Average time = 7.168 seconds (3 rounds), Encoding speed = 1508.30x

-j10: Average time = 7.333 seconds (3 rounds), Encoding speed = 1474.36x

-j11: Average time = 6.644 seconds (3 rounds), Encoding speed = 1627.25x

-j12: Average time = 6.461 seconds (3 rounds), Encoding speed = 1673.51x

ktf_v2 (MD5: 08125e8c74864eb66cf810da273c7c73):

-j1: Average time = 22.855 seconds (3 rounds), Encoding speed = 473.06x

-j2: Average time = 20.627 seconds (3 rounds), Encoding speed = 524.18x

-j3: Average time = 10.813 seconds (3 rounds), Encoding speed = 999.91x

-j4: Average time = 8.088 seconds (3 rounds), Encoding speed = 1336.85x

-j5: Average time = 7.196 seconds (3 rounds), Encoding speed = 1502.43x

-j6: Average time = 7.021 seconds (3 rounds), Encoding speed = 1539.88x

-j7: Average time = 6.643 seconds (3 rounds), Encoding speed = 1627.58x

-j8: Average time = 6.673 seconds (3 rounds), Encoding speed = 1620.18x

-j9: Average time = 7.135 seconds (3 rounds), Encoding speed = 1515.42x

-j10: Average time = 7.220 seconds (3 rounds), Encoding speed = 1497.44x

-j11: Average time = 7.102 seconds (3 rounds), Encoding speed = 1522.46x

-j12: Average time = 6.323 seconds (3 rounds), Encoding speed = 1709.95x

I would not dare to draw a conclusion here, I can't see any significant differences. But maybe your mods don't show at -7.

But my performance peek at -j7 is gone...