Performance Anti-Patterns

Learning Objectives

• Identify frequent performance anti-patterns.
• Replace inefficient patterns with practical alternatives.
• Measure improvements objectively.

Common Anti-Patterns

• Nested loops for repeated lookups.
• Recomputing same expensive values inside loops.
• Excessive object creation in hot code paths.
• Using unsuitable data structures for access pattern.

Better Alternatives

• Use hash-based lookup for membership checks.
• Cache repeated computation results.
• Batch operations where possible.
• Move constant work outside loops.

Practice Tasks

1. Find one O(n^2) routine and optimize it.
2. Benchmark before and after optimization.
3. Document runtime and memory trade-offs.

Summary

Optimize based on bottlenecks, not assumptions.