Performance Comparison: Inline Strings vs. Concatenation in PHP5

When working with textual data in PHP5, developers have the option of using inline strings (e.g., "these are some words") or performing concatenation operations (e.g., 'these are ' . $foo). This raises the question of whether there is a significant performance difference between these approaches.

Inline Strings vs. Brace-Enclosed Variables

In the context of PHP5, there is negligible performance difference between using inline strings (case 1) and brace-enclosed variables (case 2). Both methods involve simple string substitution at runtime and exhibit similar execution times.

Concatenation vs. Inline Strings or Brace-Enclosed Variables

Using concatenation (case 3) can introduce a noticeable performance overhead compared to inline strings or brace-enclosed variables. This is because concatenation requires additional steps, such as variable evaluation and string manipulation, which can take longer to execute.

Performance Benchmarking

Benchmarking tests have consistently shown that the performance difference between inline strings, brace-enclosed variables, and concatenation is negligible in recent versions of PHP. For example, a test conducted in January 2012 revealed the following results:

• Single quotes: 0.061846971511841 seconds
• Double quotes: 0.061599016189575 seconds

Conclusion

Based on these benchmarks and the evolution of PHP over time, it is evident that the performance difference between inline strings, brace-enclosed variables, and concatenation in PHP5 is largely irrelevant. The choice of approach should therefore be based on factors such as readability, maintainability, and personal preference, rather than any concerns about execution speed.