Normalization improves writes, may slow reads (more joins). Denormalize for read-heavy systems after profiling. Trade-off: integrity vs speed.

Normalized: Better writes, more joins

Denormalized: Faster reads, redundant data

Measure before denormalizing

Consider materialized views for reporting

Over-normalizing (beyond 3NF rarely needed)

Denormalizing prematurely without measurements

Storing comma-separated values (violates 1NF)

Missing foreign keys between tables