Is there a mechanism in neurons to temporarily increase membrane resistance?

I was just learning how electrical signals travel down the neuron and learned that electrical signal flowing out through the membrane significantly hinders the voltage to move down the axon. This seems like a "bad" thing, in that it reduces the efficiency of neurons to pass information.
First of all, is this assumption true?

Second, if it is true, then I was wondering if there are chemicals, whether produced internally or we take, that improves this process.