Will ice cream freeze faster with frozen brine or adding salt to ice? I've been making some ice cream without a ice cream maker, using salt, ice, mixer and steel canister since I can't get a ice cream machine around here and its fun. It works pretty good but it seems slower than a simple ice cream machine that uses a freezer bowl. And the freezer wall volume seems smaller than the amount of ice I use.

Will using a frozen brine (if I can even freeze it) or liquid cool faster than 
using frozen ice and then adding salt to melt it and lower the temperature? whats the difference? Is temperature all the matter? (liquid brine at -10c vs ice at 0)
any other factors that can contribute to the time it takes to freeze the mixture?
Any idea what coolant those bowls use? (seems to freeze at freezer temps).
If the brine melts at the same temperature you reach with the ice and salt, then it should take the same time to freeze the ice cream since the freezing time depends on heat transfer. The benefit of frozen brine is that there is more heat capacity in the frozen brine than in ice-salt cooled water, so the ice-salt water may become warmer than the frozen brine. 

It may be that there is poor heat transfer from the cream to the ice so it takes longer than you think. Also, if you are the one turning the crank, time seems to stretch out since your muscles get tired and yet the ice cream is still not frozen.