Latency is always present

What Your Computer Does While You Wait : Gustavo Duarte

Many discrete wait periods are required when accessing memory. The electrical protocol for access calls for delays after a memory row is selected, after a column is selected, before data can be read reliably, and so on. The use of capacitors calls for periodic refreshes of the data stored in memory lest some bits get corrupted, which adds further overhead. Certain consecutive memory accesses may happen more quickly but there are still delays, and more so for random access. Latency is always present.