Regex Performance Tester

Why Test Regex Performance?

Regular expressions can be powerful, but poorly written patterns can cause significant performance issues, especially when processing large amounts of text or running in loops.

Common Performance Pitfalls

• Catastrophic backtracking: Nested quantifiers like (a+)+ can cause exponential time complexity
• Greedy vs lazy: Understanding when to use * vs *?
• Unnecessary capturing groups: Use non-capturing groups (?:...) when you don't need the match
• Character classes: [0-9] is faster than \d in some engines

Best Practices

• Be specific rather than using .*
• Use anchors ^ and $ when appropriate
• Test with realistic data volumes
• Consider using non-backtracking patterns when possible