diff --git a/readme.en.html b/readme.en.html
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@@ -5,10 +5,10 @@
 <meta http-equiv="Content-Type" content="text/html; charset=us-ascii">
 <meta http-equiv="Content-Style-Type" content="text/css">
 <link rel="stylesheet" type="text/css" href="style.css">
-<title>Ut Video Codec Suite 22.3.0 readme (English)</title>
+<title>Ut Video Codec Suite 22.4.0 readme (English)</title>
 </head>
 <body>
-<h1>Ut Video Codec Suite 22.3.0 readme (English)</h1>
+<h1>Ut Video Codec Suite 22.4.0 readme (English)</h1>
 <hr>
 <h2 id="copyright_notice">Copyright Notice</h2>
 <p>Ut Video Codec Suite<br>Copyright &copy; 2008-2021  UMEZAWA Takeshi</p>
@@ -98,6 +98,14 @@ <h2 id="fourcc">List of FourCC</h2>
 <h2 id="donations">About Donations</h2>
 <p>Ut Video Codec Suite is a free software. Donations to support development are always welcome. For more information, visit <a href="http://umezawa.dyndns.info/wordpress/?page_id=1577">&quot;About Donations&quot; page</a>.</p>
 <h2 id="history">Version history</h2>
+<h3>Version 22.4.0</h3>
+<dl>
+<dt>Performance Improvements</dt><dd><ul>
+<li>UMxx: Speed up encoding on AVX512-VBMI2 capable processors.</li>
+<li>UMxx: Speed up decoding in case of inter-frame compression.</li>
+<li>all: Speed up decoding to RGB32/RGBA/YUY2/UYVY on AVX512-VBMI2 capable processors.</li>
+</ul></dd>
+</dl>
 <h3>Version 22.3.0</h3>
 <dl>
 <dt>Performance Improvements</dt><dd><ul>
diff --git a/readme.ja.html b/readme.ja.html
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--- a/readme.ja.html
+++ b/readme.ja.html
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 <meta http-equiv="Content-Type" content="text/html; charset=shift_jis">
 <meta http-equiv="Content-Style-Type" content="text/css">
 <link rel="stylesheet" type="text/css" href="style.css">
-<title>Ut Video Codec Suite 22.3.0 readme i“ú–{Œêj</title>
+<title>Ut Video Codec Suite 22.4.0 readme i“ú–{Œêj</title>
 </head>
 <body>
-<h1>Ut Video Codec Suite 22.3.0 readme i“ú–{Œêj</h1>
+<h1>Ut Video Codec Suite 22.4.0 readme i“ú–{Œêj</h1>
 <hr>
 <h2 id="copyright_notice">’˜ìŒ •\Ž¦</h2>
 <h3>‰pŒê</h3>
@@ -116,6 +116,14 @@ <h3>Windows</h3>
 <h2 id="nicovideo">ƒjƒRƒjƒR“®‰æ‚ÌƒRƒ“ƒeƒ“ƒcƒcƒŠ[‚É‚Â‚¢‚Ä</h2>
 <p>ƒjƒRƒjƒR“®‰æ‚É‚¨‚¢‚ÄAƒRƒ“ƒeƒ“ƒcƒcƒŠ[‚Ìeì•i‚Æ‚µ‚ÄŽw’è‚·‚é‚½‚ß‚ÉA<a href="http://seiga.nicovideo.jp/seiga/im1922939">Ã‰æ</a>‚ð“Še‚µ‚Ä‚ ‚è‚Ü‚·i2012”N4ŒŽ2“ú‚ÉÄ“Še‚µ‚Ü‚µ‚½jBUt Video Codec Suite ‚ðŽg—p‚µ‚Äì¬‚³‚ê‚½“®‰æ‚ð“Še‚ÌÛ‚ÍAeì•i‚Æ‚µ‚ÄŽw’è‚µ‚Ä‚¢‚½‚¾‚¯‚é‚Æ—ã‚Ý‚É‚È‚è‚Ü‚·B</p>
 <h2 id="history">‰ü”Å—š—ð</h2>
+<h3>ƒo[ƒWƒ‡ƒ“ 22.4.0</h3>
+<dl>
+<dt>«”\Œüã</dt><dd><ul>
+<li>UMxx: AVX512-VBMI2 ‚ªŽg‚¦‚éŠÂ‹«‚Å‚ÌƒGƒ“ƒR[ƒh‚ð‚‘¬‰»‚µ‚½B</li>
+<li>UMxx: ƒtƒŒ[ƒ€ŠÔˆ³k‚ÌƒfƒR[ƒh‚ð‚‘¬‰»‚µ‚½B</li>
+<li>all: AVX512-VBMI2 ‚ªŽg‚¦‚éŠÂ‹«‚Å‚Ì RGB32/RGBA/YUY2/UYVY ‚Ö‚ÌƒfƒR[ƒh‚ð‚‘¬‰»‚µ‚½B</li>
+</ul></dd>
+</dl>
 <h3>ƒo[ƒWƒ‡ƒ“ 22.3.0</h3>
 <dl>
 <dt>«”\Œüã</dt><dd><ul>
