Hashcat slows down after staring attack.

Hi everyone.    

I have a Titan xp getting awesome bench marks.  But When it comes down to using hashcat it slows down drastically.

I am testing it on hash mode 2500 wpa,  benchmarked hash mode 2500.  655.8 kH's 

When I go to use hashcat it slows down to 8000-9000 H's.

Test file password is 1234567890

And when I use hashcat with -w 3 or 4. It just hangs at 0% progress.    But gpu is utilized almost 100%

What do I have to fix to make it work properly ?

Gpu drivers 390.25
Cuda Toolkit 9.1