Latency vs throughput
Latency is the time to perform some action or to produce some result.
Throughput is the number of such actions or results per unit of time.
Generally, you should aim for maximal throughput with acceptable latency.
Definition of terms
Let us attempt to define those two terms:
Latency is the time required to perform some action or to produce some result. Latency is measured in units of time -- hours, minutes, seconds, nanoseconds or clock periods.
Throughput is the number of such actions executed or results produced per unit of time. This is measured in units of whatever is being produced (cars, motorcycles, I/O samples, memory words, iterations) per unit of time. The term "memory bandwidth" is sometimes used to specify the throughput of memory systems.