with a type 6 you will have to fire about 3 full loads, means it takes 3 rechargecycles to complete the mine .. with an ASP it takes 2 and with an python just one
This is probably more related to your power plant, I fitted an ASP out last night and, using a medium mining laser, 4 pips to weapons, it had a steady stream what would have taken off 4 bars before the asteroid was completely mined.
An 8 bin processor was the largest I could fit, but it worked well.
Profitable vs a Hi/HazRez? Nope. Having a good source of missions would help it well.