Is file_get_contents slower than include?

Since include will evaluate the content of the files, e.g. run in through the PHP interpreter and also use the include_path to find files, I'd say include is slower. file_get_contents will just treat the contents of a file as string. Less overhead, more speed.

From the manual page:

file_get_contents() is the preferred way to read the contents of a file into a string. It will use memory mapping techniques if supported by your OS to enhance performance.

However, if you are after outputting the file, instead of getting it into a string, readfile() is even a tiny bit faster than file_get_contents. Given that include'ing will output any non PHP content as well, this likely more likely what you are after I guess.

Revised benchmark on my desktop machine:

$start1 = microtime(1);for($i=0; $i<100000; $i++) {    include 'log.txt';}$end1 = microtime(1) - $start1;

and

$start2 = microtime(1);for($i=0; $i<100000; $i++) {    echo file_get_contents('log.txt');}$end2 = microtime(1) - $start2;

and

$start3 = microtime(1);for($i=0; $i<100000; $i++) {    readfile('log.txt');}$end3 = microtime(1) - $start3;

Result

echo PHP_EOL, $end1, // 137.577358961     PHP_EOL, $end2, // 136.229552984     PHP_EOL, $end3; // 136.849179029

file_get_contents and include doesn't do the same thing:

• file_get_contents reads the content of a file, and returns it as a string
• include will execute the content of the file.

About the speed, without an opcode cache, I suppose file_get_contents should theoretically be faster, as it does less calculation (no compilation/execution of the code).

Still, what matters the most is probably what you are trying to do: if you only want to read a file, you should use file_get_contents.

If all you want to do is output the file contents, you should be using readfile(). This is faster and less memory intensive than file_get_contents()