I suspect you are taking time you don't need to. We tap 6061 and leaded steel mostly 10-32, 10-24, 1/4-20, M6x1, 3/8-16, 5/16-18 and 1/4 NPT and just use a water soluble coolant. The coolant is Shell Dromus B, not that much different to the Blaser or Harnesfeger (is that the name?) although reps for those company will probably want to scream at me for saying that. Our coolant mix is fairly rich at a dilution of 1 in 10 and we have found that tapping is sensitive to the dilution factor. At 1 in 20 we definitely get problems anything richer than 1 in 15 seems okay. Our 1 in 10 is used mostly to prevent rust spotting on the leaded steel parts and to a lesser extent on machine tables and vises. All our machines have flood coolant with high capacity pumps so the tapping is done fully immersed. The spindle speed is always 1000 rpm and on some 6061 parts that are tapped about .85" deep in a blind hole we peck once or twice.
Occasionally for making fixtures I have tapped 1/2-13 and 9/16-18 in cold rolled and hot rolled steel with the same coolant mix same rpm without problems