What is cache locality and why does it matter?
PICTURE THIS: DJANGO MVT
Simple meaning
CPUs fetch memory in cache lines.
WHY — Performance instead of guessing?
Why interviewers care about Performance:
who only read docs from people who shipped.
and tied to C++ work.
Name the idea, why it exists, then one short example.
End with when you use it and one common pitfall.
STEPS — What happens step by step?
Before you speak the answer, walk the interviewer through these steps:
- 1CPUs fetch memory in
cache lines.
- 2Contiguous data like vector
walks faster than pointer-chasing lists.
- 3Algorithm choice plus data
layout decides real speed, not only Big-O.
- 4Give an example
One tiny concrete case you can say aloud.
- 5Common mistake
What juniors usually get wrong.
- 6Close
When you pick this over the alternative.
EXAMPLE — See it in action
Here's a short line you can speak, broken into clear beats:
Note: Adapt this scaffold to your own project — keep it under 60–90 seconds.
Key takeaway
CPUs fetch memory in cache lines. Contiguous data like vector walks faster than pointer-chasing lists.