Mostly what you want is something that's going to make the cutter run cooler. You can do this in any combination of ways - run something that carries away the heat, run something that reduces friction between the cutter and the work, make sure that you're running a tool with the right geometry, etc.
You might get a lot of the results you're looking for using compressed air to cool and clear the workspace. Some of the heat is almost certainly from chip recutting, so clearing the field for the cutter can only help (plus it eliminates scrubbing, something to be desired).
Adding to that is the suggestion given to use Koolmist - this is (usually) a soluble oil in water mix that's aerolsized with compressed air and sprayed onto the work and tool. The aerosolized lube is usually a lot cooler than the air and the remaining liquid takes heat from the cutter directly and by lubricating it. The downside of something like that is the water - you're going to need something under the work that doesn't soak it up, and you usually want to clean up after using it. Another problem is that the spray mists into the air and some folks can develop sensitivities to it over time.
I use something called a Trico Microdrop system. It aerolsizes a synthetic oil and only uses the air and oil to cool. The nice thing is that oil usage is minimal, it doesn't mist and you don't have watery crap all of the workspace when you're done. Downside is that even the knockoffs are expensive.
I'd do 2 things: run compressed air with some locline to the tool to clear the area and use the proper cutter geometries for brass and galvanized, separating the tooling so that a brass tool is never used on steel. See if that doesn't take care of the majority of the problem.