diff --git a/.gitattributes b/.gitattributes
new file mode 100644
index 00000000..2d2f5a38
--- /dev/null
+++ b/.gitattributes
@@ -0,0 +1,10 @@
+/.gitattributes export-ignore
+/.gitignore     export-ignore
+/.github        export-ignore
+/.php_cs.dist   export-ignore
+/.travis.yml    export-ignore
+/build.xml      export-ignore
+/phpunit.xml    export-ignore
+/tests          export-ignore
+
+*.php diff=php
diff --git a/ChangeLog.md b/ChangeLog.md
index 76ccd877..d14aaddf 100644
--- a/ChangeLog.md
+++ b/ChangeLog.md
@@ -2,6 +2,29 @@
 
 All notable changes are documented in this file using the [Keep a CHANGELOG](http://keepachangelog.com/) principles.
 
+## [3.0.6] - 2023-03-02
+
+### Changed
+
+* Do not use implicitly nullable parameters
+
+## [3.0.5] - 2023-03-01
+
+* No code changes, only updated `.gitattributes` to not export non-essential files.
+
+## [3.0.4] - 2023-05-07
+
+### Changed
+
+* [#118](https://github.com/sebastianbergmann/diff/pull/118): Improve performance of `MemoryEfficientLongestCommonSubsequenceCalculator`
+* [#119](https://github.com/sebastianbergmann/diff/pull/119): Improve performance of `TimeEfficientLongestCommonSubsequenceCalculator`
+
+## [3.0.3] - 2020-11-30
+
+### Changed
+
+* Changed PHP version constraint in `composer.json` from `^7.1` to `>=7.1`
+
 ## [3.0.2] - 2019-02-04
 
 ### Changed
@@ -46,6 +69,10 @@ All notable changes are documented in this file using the [Keep a CHANGELOG](htt
 
 * This component is no longer supported on PHP 5.6
 
+[3.0.6]: https://github.com/sebastianbergmann/diff/compare/3.0.5...3.0.6
+[3.0.5]: https://github.com/sebastianbergmann/diff/compare/3.0.4...3.0.5
+[3.0.4]: https://github.com/sebastianbergmann/diff/compare/3.0.3...3.0.4
+[3.0.3]: https://github.com/sebastianbergmann/diff/compare/3.0.2...3.0.3
 [3.0.2]: https://github.com/sebastianbergmann/diff/compare/3.0.1...3.0.2
 [3.0.1]: https://github.com/sebastianbergmann/diff/compare/3.0.0...3.0.1
 [3.0.0]: https://github.com/sebastianbergmann/diff/compare/2.0...3.0.0
diff --git a/composer.json b/composer.json
index 59520e99..fe2d77fe 100644
--- a/composer.json
+++ b/composer.json
@@ -15,7 +15,7 @@
         }
     ],
     "require": {
-        "php": "^7.1"
+        "php": ">=7.1"
     },
     "require-dev": {
         "phpunit/phpunit": "^7.5 || ^8.0",
diff --git a/src/Differ.php b/src/Differ.php
index 3c90a5a1..74e31449 100644
--- a/src/Differ.php
+++ b/src/Differ.php
@@ -64,7 +64,7 @@ public function __construct($outputBuilder = null)
      *
      * @return string
      */
-    public function diff($from, $to, LongestCommonSubsequenceCalculator $lcs = null): string
+    public function diff($from, $to, ?LongestCommonSubsequenceCalculator $lcs = null): string
     {
         $diff = $this->diffToArray(
             $this->normalizeDiffInput($from),
@@ -92,7 +92,7 @@ public function diff($from, $to, LongestCommonSubsequenceCalculator $lcs = null)
      *
      * @return array
      */
-    public function diffToArray($from, $to, LongestCommonSubsequenceCalculator $lcs = null): array
+    public function diffToArray($from, $to, ?LongestCommonSubsequenceCalculator $lcs = null): array
     {
         if (\is_string($from)) {
             $from = $this->splitStringByLines($from);
diff --git a/src/Exception/ConfigurationException.php b/src/Exception/ConfigurationException.php
index 78f16fde..f57ec950 100644
--- a/src/Exception/ConfigurationException.php
+++ b/src/Exception/ConfigurationException.php
@@ -24,7 +24,7 @@ public function __construct(
         string $expected,
         $value,
         int $code = 0,
-        \Exception $previous = null
+        ?\Exception $previous = null
     ) {
         parent::__construct(
             \sprintf(
diff --git a/src/MemoryEfficientLongestCommonSubsequenceCalculator.php b/src/MemoryEfficientLongestCommonSubsequenceCalculator.php
index 82dc20c8..68670ddd 100644
--- a/src/MemoryEfficientLongestCommonSubsequenceCalculator.php
+++ b/src/MemoryEfficientLongestCommonSubsequenceCalculator.php
@@ -71,7 +71,12 @@ private function length(array $from, array $to): array
                 if ($from[$i] === $to[$j]) {
                     $current[$j + 1] = $prev[$j] + 1;
                 } else {
-                    $current[$j + 1] = \max($current[$j], $prev[$j + 1]);
+                    // don't use max() to avoid function call overhead
+                    if ($current[$j] > $prev[$j + 1]) {
+                        $current[$j + 1] = $current[$j];
+                    } else {
+                        $current[$j + 1] = $prev[$j + 1];
+                    }
                 }
             }
         }
diff --git a/src/TimeEfficientLongestCommonSubsequenceCalculator.php b/src/TimeEfficientLongestCommonSubsequenceCalculator.php
index 97dadbd5..690b46fe 100644
--- a/src/TimeEfficientLongestCommonSubsequenceCalculator.php
+++ b/src/TimeEfficientLongestCommonSubsequenceCalculator.php
@@ -33,12 +33,24 @@ public function calculate(array $from, array $to): array
 
         for ($i = 1; $i <= $fromLength; ++$i) {
             for ($j = 1; $j <= $toLength; ++$j) {
-                $o          = ($j * $width) + $i;
-                $matrix[$o] = \max(
-                    $matrix[$o - 1],
-                    $matrix[$o - $width],
-                    $from[$i - 1] === $to[$j - 1] ? $matrix[$o - $width - 1] + 1 : 0
-                );
+                $o = ($j * $width) + $i;
+
+                // don't use max() to avoid function call overhead
+                $firstOrLast = $from[$i - 1] === $to[$j - 1] ? $matrix[$o - $width - 1] + 1 : 0;
+
+                if ($matrix[$o - 1] > $matrix[$o - $width]) {
+                    if ($firstOrLast > $matrix[$o - 1]) {
+                        $matrix[$o] = $firstOrLast;
+                    } else {
+                        $matrix[$o] = $matrix[$o - 1];
+                    }
+                } else {
+                    if ($firstOrLast > $matrix[$o - $width]) {
+                        $matrix[$o] = $firstOrLast;
+                    } else {
+                        $matrix[$o] = $matrix[$o - $width];
+                    }
+                }
             }
         }