Why does the nervous system have synapses if they slow down transmission?

Synapses are chemical connections between neurons which do indeed slow down transmission. However, they provide the nervous system with many benefits that could not be achieved without them: They ensure that information flow is in one direction. Since neurotransmitter - the chemical signal - is only produced in the presynaptic nerve terminal, and the receptor for this neurotransmitter is only present on the postsynaptic neuron, the signal can only be transmitted from presynaptic to postsynaptic neuron, and not the other way around. They also allow one presynaptic neuron to connect to many postsynaptic neurons. Here, all the postsynaptic neurons possess the receptor for the neurotransmitter released by the presynaptic neuron. This allows a signal to be spread across the body more quickly and efficiently. For example, during a reflex movement (for example, after touching a hot stove), the sensory neuron activated by the heat can form synapses with many different motor neurons controlling the muscles in the arm, allowing a quick and coordinated movement.