Memory Latency Explained Software Execution
Modern CPUs are incredibly fast — but they can’t compute without data. And when data isn’t already in cache, the processor has to wait.
That waiting time is memory latency.
In this video, we explain what memory latency actually is, how it’s measured in cycles and nanoseconds, and why it often defines real-world performance more than raw clock speed. You’ll see how latency differs from bandwidth, why cache misses are expensive, and how modern CPUs try to hide latency using out-of-order execution, prefetching, and memory-level parallelism.
We also explore why certain data structures perform poorly, why sequential memory access is usually faster than random access, and why optimizing memory patterns can matter more than optimizing arithmetic.
This episode continues the memory hierarchy arc of the Software Execution series. After understanding caches, memory latency is the next critical piece in building a realistic performance model.
If you want to understand why your CPU sometimes “waits” — and what that means for software design — this video gives you the foundation.