My PHP Performance Benchmarks

PHP version 4.4.8 is running on this server.

Check if a String is empty

Method	Undefined	Null	False	Empty string	String "0"	String "1"	Long string	Summary	Index
`if (!$var)`	3.1 ms	1.1 ms	1.1 ms	1.1 ms	1.1 ms	0.6 ms	0.6 ms	8.6 ms	128
`if (empty($var))`	1.1 ms	51.1 ms	1.1 ms	1.1 ms	1.1 ms	0.6 ms	0.6 ms	56.6 ms	845
`if ($var == "")`	3.2 ms	1.2 ms	271.2 ms	1.2 ms	0.9 ms	0.9 ms	2,454.5 ms	2,732.9 ms	40844
`if ("" == $var)`	403.2 ms	1.1 ms	1.2 ms	845.2 ms	0.7 ms	0.7 ms	0.7 ms	1,252.8 ms	18723
`if ($var === "")`	2.6 ms	0.6 ms	0.6 ms	1.2 ms	0.6 ms	0.6 ms	0.6 ms	6.7 ms	100
`if ("" === $var)`	691.1 ms	0.6 ms	0.6 ms	1.2 ms	0.6 ms	0.6 ms	0.6 ms	695.2 ms	10390
`if (strcmp($var, "") == 0)`	4.3 ms	822.3 ms	2.2 ms	2.1 ms	1.5 ms	1.5 ms	352.2 ms	1,186.1 ms	17726
`if (strcmp("", $var) == 0)`	14.4 ms	2.4 ms	2.3 ms	632.2 ms	1.5 ms	1.5 ms	1.5 ms	655.9 ms	9802
`if (strlen($var) == 0)`	4.0 ms	182.0 ms	2.0 ms	1.8 ms	1.3 ms	1.3 ms	1.3 ms	193.5 ms	2892
`if (!strlen($var))`	573.8 ms	1.9 ms	1.9 ms	1.7 ms	1.2 ms	391.2 ms	1.2 ms	972.8 ms	14539

My conclusion: In most cases, use empty() because it does not trigger a warning when used with undefined variables. Note that empty("0") returns true. Use strlen() if you want to detect "0". Try to avoid == at all because it may cause strange behaviour (e.g. "9a" == 9 returns true). Prefer === over == and !== over != if possible because it does compare the variable types in addition to the contents.

Check if a String contains another String

Method	Not found	Found at the start	Found in the middle	Found at the end	Summary	Index
`strstr($haystack, $needle)`	1.2 ms	2.1 ms	1.7 ms	1.8 ms	6.8 ms	100
`strpos($haystack, $needle) !== false`	1.5 ms	1,072.1 ms	2.1 ms	2.2 ms	1,077.8 ms	15903
`strstr($haystack, $needle) !== false`	1.5 ms	2.4 ms	402.1 ms	2.2 ms	408.2 ms	6023
`stristr($haystack, $needle)`	2.9 ms	3.8 ms	313.5 ms	3.6 ms	323.8 ms	4777
`preg_match("/$needle/", $haystack)`	2.1 ms	672.5 ms	130.3 ms	2.8 ms	807.7 ms	11918
`preg_match("/$needle/i", $haystack)`	2.2 ms	2.5 ms	292.7 ms	2.9 ms	300.4 ms	4432
`preg_match("/$needle/S", $haystack)`	2.1 ms	2.5 ms	531.6 ms	2.8 ms	539.0 ms	7953
`ereg($needle, $haystack)`	2.9 ms	53.3 ms	650.1 ms	106.9 ms	813.3 ms	12000

My conclusion: It does not matter if you use strstr() or strpos(). Use the preg…() functions only if you need the power of regular expressions. Never use the ereg…() functions.

Check if a String starts with another String

Method	Not found	Found at the start	Found in the middle	Found at the end	Summary	Index
`strncmp($haystack, $needle, strlen($needle)) === 0`	2.1 ms	2.1 ms	2.1 ms	2.1 ms	8.4 ms	139
`strncmp($haystack, "Test", 4) === 0`	101.7 ms	1.7 ms	338.1 ms	1.7 ms	443.2 ms	7269
`strncasecmp($haystack, $needle, strlen($needle)) === 0`	2.1 ms	2.1 ms	2.1 ms	32.1 ms	38.4 ms	629
`strpos($haystack, $needle) === 0`	1.5 ms	1.5 ms	1.5 ms	1.6 ms	6.1 ms	100
`substr($haystack, 0, strlen($needle)) === $needle`	2.3 ms	232.3 ms	2.3 ms	2.3 ms	239.3 ms	3924
`strcmp(substr($haystack, 0, strlen($needle)), $needle) === 0`	3.0 ms	33.0 ms	3.1 ms	3.0 ms	42.2 ms	692
`preg_match("/^" . preg_quote($needle, "/") . "/", $haystack)`	45.0 ms	5.0 ms	114.9 ms	4.9 ms	169.9 ms	2786

My conclusion: strpos() is very fast and can be used in almost all cases. strncmp() is good if you are looking for a constant length needle.

Check if a String ends with another String

Method	Not found	Found at the start	Found in the middle	Found at the end	Summary	Index
`substr($haystack, strlen($haystack) - strlen($needle)) === $needle`	3.0 ms	3.2 ms	3.0 ms	53.6 ms	62.8 ms	117
`substr($haystack, -strlen($needle)) === $needle`	2.5 ms	2.4 ms	132.5 ms	2.4 ms	139.8 ms	261
`strcmp(substr($haystack, -strlen($needle)), $needle) === 0`	3.3 ms	3.7 ms	43.3 ms	3.3 ms	53.5 ms	100
`preg_match("/" . preg_quote($needle, "/") . "$/", $haystack)`	115.8 ms	5.8 ms	146.0 ms	5.9 ms	273.6 ms	511

My conclusion: Using substr() with a negative position is a good trick.

Replace a String inside another String

Method	Not found	Found at the start	Found in the middle	Found at the end	Summary	Index
`str_replace($search, $replace, $subject)`	3.0 ms	3.6 ms	3.2 ms	1,073.2 ms	1,083.0 ms	2988
`preg_replace("/$search/", $replace, $subject)`	3.7 ms	24.3 ms	4.1 ms	4.1 ms	36.2 ms	100
`preg_replace("/$search/S", $replace, $subject)`	45.5 ms	4.2 ms	4.1 ms	4.1 ms	58.0 ms	160
`ereg_replace($search, $replace, $subject)`	4.7 ms	6.8 ms	13.1 ms	19.5 ms	44.2 ms	122

My conclusion: Never use the ereg…() functions.

Trim Characters from the Beginning and End of a String

Method	Not found	Found at start	Found at end	Found at both sides	Summary	Index
`trim($string, ",")`	0.4 ms	0.4 ms	0.4 ms	0.4 ms	1.8 ms	100
`preg_replace('/^,\|,$/', "", $string)`	10.4 ms	10.4 ms	10.4 ms	10.4 ms	41.8 ms	2383
`preg_replace('/^,\|,$/m', "", $string)`	16.6 ms	16.6 ms	262.9 ms	151.8 ms	447.9 ms	25569
`preg_replace('/^,+\|,+$/', "", $string)`	0.8 ms	0.8 ms	0.8 ms	0.8 ms	3.1 ms	178
`preg_replace('/^,+\|,+$/m', "", $string)`	0.8 ms	0.8 ms	40.8 ms	0.8 ms	43.2 ms	2464
`preg_replace('/^,+/', "", preg_replace('/,+$/', "", …))`	1.2 ms	1.2 ms	1.2 ms	1.2 ms	4.9 ms	280

My conclusion: Always benchmark your regular expressions! In this case, with .* you also replace nothing with nothing which takes time because there is a lot of “nothing” in every string.

Split a String into an Array

Method	Empty string	Single occurrence	Multiple occurrences	Summary	Index
`explode(",", $string)`	1.5 ms	1.8 ms	213.8 ms	217.2 ms	766
`split(",", $string)`	1.6 ms	351.8 ms	1,481.5 ms	1,834.9 ms	6474
`preg_split("/,/", $string)`	1.9 ms	2.4 ms	24.1 ms	28.3 ms	100
`preg_match_all('/[^,]+/', $string, $matches)`	2.8 ms	4.5 ms	28.3 ms	35.6 ms	126

My conclusion: Don't use split(). It's deprecated in PHP 5.3 and will be removed in PHP 6.

Loop a numerical indexed Array of Strings

Method	Summary	Index
`for ($i = 0; $i < count($array); $i++)`	95.0 ms	4483
`for ($i = 0, $count = count($array); $i < $count; $i++)`	3.5 ms	164
`for ($i = count($array) - 1; $i >= 0; $i--)`	2.7 ms	128
`for ($i = count($array) - 1; $i >= 0; --$i)`	2.6 ms	123
`$i = count($array); while ($i--)`	2.1 ms	100

My conclusion: count() is horribly slow. Always precalculate it, if possible.

The single vs. double Quotes Myth

Method	Summary	Index
`'contains no dollar signs'`	1.8 ms	101
`"contains no dollar signs"`	1.8 ms	101
`'$variables $are $not $replaced'`	1.8 ms	100
`"\$variables \$are \$not \$replaced"`	1.9 ms	109
`"$variables $are $replaced"`	16.1 ms	909
`$variables . ' ' . $are . ' ' . $replaced`	22.9 ms	1292
`$variables . " " . $are . " " . $replaced`	22.3 ms	1258

My conclusion: It does not matter if you use single or double quotes at all. The inclusion of variables has a measurable effect, but that's independent from the quotes.