It takes 13.3s to make Potin Dust in a LV mixer which can directly be smelted into ingots while using the ABF it takes 40s to make Liquid Potin at HV. I'm assuming the former is un-intended.

Using latest GT from Github and IC2 2.2.827. Also using latest GT++ from Github.

I see lately you've posted a few issues.
If possible could you adhere to the guidelines for issue creation?
https://github.com/draknyte1/GTplusplus/wiki/Github-Issue-Format

Times taken for ABS'ing has changed a lot lately.
It's not intended per-say, but the times are generated totally differently.
This will apply to nearly any material without a blast furnace recipe.

Will do. For minor issues should I open seperate issues for each of them or bunch them all together?

Whichever you prefer, I am easy going.
Just make sure the title reflects either 'Thing is broken' or 'Collection of issues' sort of thing. :)