No. It does a little more than a 5cp envenom, but its best to save 4-5 CPs and envenom cause if you get a PB off the envenom it'll make up for all that lost damage plus a ton.
That's stupid. Mut once or save CP for an envenom. 'Optimally' you would not switch at all, but this is mostly if the classes which are actually efficient at it are not switching enough.