Letâs be realâmost PHP performance issues arenât caused by exotic edge cases. Theyâre caused by small mistakes that quietly accumulate until your server starts sweating.
Over the years, Iâve fallen into every performance trap in the bookâand watched others do the same. So hereâs a list of the top 10 PHP performance pitfalls Iâve seen (and fixed) in the wild.
If youâre leading or maintaining a PHP codebase, this oneâs for you.
1. Loading Everything All at Once
If your app is pulling thousands of rows from MySQL just to paginate them later, thatâs not paginationâthatâs punishment.
Fix: Always use LIMIT and OFFSET in your queries. Better yet, consider cursor-based pagination for large datasets.
2. Too Many Database Queries
The âN+1 query problemâ is a classic. Looping over 50 users and querying each userâs posts separately? Thatâs 51 queries when one will do.
Fix: Use joins, or fetch data in batches. If youâre using an ORM, dig into eager loading.
3. Uncached Configs and Constants
Calling get_setting('something') in every request when it couldâve been cached once? Yeah, that adds up.
Fix: Use config caching (php artisan config:cache in Laravel, for example), or store static settings in memory (APCu, Redis, etc).
4. Heavy Bootstrapping
Every request doesnât need to boot your entire app if youâre just handling a webhook or an API call.
Fix: Segment your application entry points and avoid overloading minimal-use cases with full bootstrap costs.
5. Overusing Autoloading in Loops
Autoloading classes inside tight loops leads to IO and CPU hits you didnât ask for.
Fix: Make sure classes used in loops are already loaded. Composerâs classmap optimization (--optimize-autoloader) helps a ton.
6. Ignoring Output Buffering
PHP sends data to the browser in chunks. But if your app flushes output inefficiently, that can slow things down or spike memory.
Fix: Use output buffering strategically. Most frameworks handle this, but know whatâs happening under the hood.
7. Unoptimized Regular Expressions
Regex is powerfulâbut expensive. One careless pattern can grind your CPU.
Fix: Benchmark your patterns. Avoid backtracking traps. And seriously, donât use regex when strpos() will do.
8. Not Using Opcache
If youâre not running PHP with Opcache enabled, youâre throwing away free performance.
Fix: Turn on Opcache in your php.ini and monitor the cache hit rate. Itâs easy and gives instant gains.
9. No Profiling or Monitoring
How can you fix slow code if you donât know whatâs slow?
Fix: Use tools like Blackfire, Xdebug, or Laravel Telescope. Even a simple log of request durations can point you to issues fast.
10. Overengineering
The worst performance killer? Complexity.
Iâve seen apps slow down just from trying to be too clever: abstracting every function, writing unnecessary layers of logic, or throwing design patterns at problems that didnât exist.
Fix: Write simple code that does the job. Readability often equals performance.
Final Thought
The truth is, most PHP performance issues are 20% code and 80% awareness. If youâre mindful of what your app is actually doingâhow it queries, caches, renders, and routesâyouâre already ahead of the pack.
So the next time your app feels sluggish, donât panic. Run through this list, fix what you can, and move on like a pro.