We've been having quite a few issues with speed and server load, something which we'd never had to worry about in the past. We've been building more and more web apps and fewer and fewer simple websites.
We are also facing mod security restrictions on our webhost. Cartika (no longer recommended) are strapped down pretty tightly, but that makes sense. They also let us know right away if a website of ours is facing security attacks or if it is being scraped every day.
Apparently not all PHP is created equal and it is time to batten down the hatches.
Once we get to functionality we will have to put a full-fledged optimisation phase in the development cycle: the Code Optimization Phase.
In that phase we will specifically target PHP speed and security (as functionality will already be completely in place).
I will start by asking all Foliovision developers to read the article 40 Tips for optimizing your php Code. The top twenty or so are below.
- If a method can be static, declare it static. Speed improvement is by a factor of 4.
- echo is faster than print.
- Use echo's multiple parameters instead of string concatenation.
- Set the maxvalue for your for-loops before and not in the loop.
- Unset your variables to free memory, especially large arrays.
- Avoid magic like __get, __set, __autoload
- require_once() is expensive
- Use full paths in includes and requires, less time spent on resolving the OS paths.
- If you need to find out the time when the script started executing, $_SERVER[’REQUEST_TIME’] is preferred to time()
- See if you can use strncasecmp, strpbrk and stripos instead of regex
- str_replace is faster than preg_replace, but strtr is faster than str_replace by a factor of 4
- If the function, such as string replacement function, accepts both arrays and single characters as arguments, and if your argument list is not too long, consider writing a few redundant replacement statements, passing one character at a time, instead of one line of code that accepts arrays as search and replace arguments.
- It's better to use select statements than multi if, else if, statements.
- Error suppression with @ is very slow.
- Turn on apache's mod_deflate
- Close your database connections when you're done with them
- $row[’id’] is 7 times faster than $row[id]
- Error messages are expensive
- Do not use functions inside of for loop, such as for ($x=0; $x < count($array); $x) The count() function gets called each time.
- Incrementing a local variable in a method is the fastest. Nearly the same as calling a local variable in a function.
- Incrementing a global variable is 2 times slow than a local var.
- Incrementing an object property (eg. $this->prop++) is 3 times slower than a local variable.