PHP Performance Optimization: String Handling, Statements, Functions, Variables, Arrays and Architecture

1. String handling – Prefer built‑in string functions (e.g., str_replace , strtr ) over regular expressions; use strtr for single‑character replacements; compress large strings with gzcompress / gzuncompress ; output strings with commas in echo ; and always use single quotes for plain strings.

2. Statements – Avoid the error‑silencing operator @ and magic methods like __autoload ; move expensive calls (e.g., count() ) out of loops; use the ternary operator for simple conditions; prefer switch / case over multiple if / else if ; hide sensitive data with error_reporting() and proper PHP opening tags.

3. Functions – Use internal PHP functions whenever possible; include files with absolute paths and plain require / include instead of their *_once variants; functions are faster than class methods; static methods can be up to 1/4 faster than instance methods; pass parameters by reference when appropriate; consider C extensions for heavy‑weight logic.

4. Variables – Destroy large arrays/objects promptly; use $_SERVER['REQUEST_TIME'] instead of time() for timing; local variables are faster than globals or object properties; pre‑declare variables; prefer pre‑increment ( ++$i ) over post‑increment ( $i++ ); avoid unnecessary copies of superglobals.

5. Arrays – Use strings instead of arrays when possible; always quote array keys (e.g., $row['id'] ) for speed; avoid deep nested loops for multidimensional arrays; iterate with foreach rather than while or for .

6. Architecture – Enable gzip compression in php.ini (e.g., zlib.output_compression = On ); serve static HTML when feasible; keep PHP up‑to‑date; leverage extensions, opcode caches (APC, OPcache) and external caches like Memcached or Redis to reduce CPU and I/O overhead.