something went wrong with decred in 4way version:
looks like new avx "optimizations"

4way:
cpuminer-4way.exe -a decred --benchmark -q
********** cpuminer-opt 3.7.4 ***********
A CPU miner with multi algo support and optimized for CPUs
with AES_NI and AVX extensions.
BTC donation address: 12tdvfF7KmAsihBXQXynT6E6th2c2pByTT
Forked from TPruvot's cpuminer-multi with credits
to Lucas Jones, elmad, palmd, djm34, pooler, ig0tik3d,
Wolf0, Jeff Garzik and Optiminer.
CPU: Intel(R) Core(TM) i5-7600K CPU @ 3.80GHz
CPU features: SSE2 AES AVX AVX2
SW built on Nov 28 2017 with GCC 4.8.3
SW features: SSE2 AES AVX AVX2
Algo features: SSE2 AVX
Start mining with SSE2 AVX
[2017-12-03 02:48:25] 4 miner threads started, using 'decred' algorithm.
[2017-12-03 02:48:27] Total: 4194.31 kH, 2282.60 kH/s
[2017-12-03 02:48:30] Total: 24.57 MH, 9178.06 kH/s
[2017-12-03 02:48:35] Total: 36.62 MH, 9224.63 kH/s
[2017-12-03 02:48:40] Total: 46.12 MH, 9216.31 kH/s
avx2:
cpuminer-aes-avx2.exe -a decred --benchmark -q
********** cpuminer-opt 3.7.4 ***********
A CPU miner with multi algo support and optimized for CPUs
with AES_NI and AVX extensions.
BTC donation address: 12tdvfF7KmAsihBXQXynT6E6th2c2pByTT
Forked from TPruvot's cpuminer-multi with credits
to Lucas Jones, elmad, palmd, djm34, pooler, ig0tik3d,
Wolf0, Jeff Garzik and Optiminer.
CPU: Intel(R) Core(TM) i5-7600K CPU @ 3.80GHz
CPU features: SSE2 AES AVX AVX2
SW built on Nov 28 2017 with GCC 4.8.3
SW features: SSE2 AES AVX AVX2
Algo features: SSE2
Start mining with SSE2
[2017-12-03 02:48:06] 4 miner threads started, using 'decred' algorithm.
[2017-12-03 02:48:07] Total: 12.58 MH, 17.26 MH/s
[2017-12-03 02:48:11] Total: 35.43 MH, 23.06 MH/s
[2017-12-03 02:48:16] Total: 98.06 MH, 22.98 MH/s