NTLM Benchmark vs Mask Attack

I have 2 GTX 1080 cards, and I have run a benchmark for NTLM listed below:

Hashtype: NTLM
Speed.Dev.#1.....: 44431.8 MH/s (60.25ms)
Speed.Dev.#2.....: 44439.7 MH/s (60.07ms)
Speed.Dev.#*.....: 88871.5 MH/s


Now when I run a Mask attack my results aren't even close:

Speed.Dev.#1.....: 18905.6 MH/s (7.72ms)
Speed.Dev.#2.....: 18906.8 MH/s (7.75ms)
Speed.Dev.#*.....: 37812.4 MH/s

Command Used:
hashcat64.exe -a 3 -m 1000 hashes.txt ?a?a?a?a?a?a?a?a?a -o cracked.txt

Am i missing something to optimize my GPUs or is this expected? I am running 3.30 on Windows if it makes any difference.