diff --git a/src/common/htmlescape.cc b/src/common/htmlescape.cc
index b19bed52a..aacd51846 100644
--- a/src/common/htmlescape.cc
+++ b/src/common/htmlescape.cc
@@ -130,26 +130,25 @@ string escapeForJavaScript( string const & str )
   return result;
 }
 
-QString stripHtml( QString & tmp )
+QString stripHtml( QString tmp )
 {
-  tmp.replace(
-    QRegularExpression(
-      "<(?:\\s*/?(?:div|h[1-6r]|q|p(?![alr])|br|li(?![ns])|td|blockquote|[uo]l|pre|d[dl]|nav|address))[^>]{0,}>",
-      QRegularExpression::CaseInsensitiveOption ),
-    " " );
-  tmp.replace( QRegularExpression( "<[^>]*>" ), " " );
+  static QRegularExpression htmlRegex(
+    "<(?:\\s*/?(?:div|h[1-6r]|q|p(?![alr])|br|li(?![ns])|td|blockquote|[uo]l|pre|d[dl]|nav|address))[^>]{0,}>",
+    QRegularExpression::CaseInsensitiveOption );
+  tmp.replace( htmlRegex, " " );
+  static QRegularExpression htmlElementRegex( "<[^>]*>" );
+  tmp.replace( htmlElementRegex, " " );
   return tmp;
 }
 
-QString unescape( QString const & str, HtmlOption option )
+QString unescape( QString str, HtmlOption option )
 {
   // Does it contain HTML? If it does, we need to strip it
   if ( str.contains( '<' ) || str.contains( '&' ) ) {
-    QString tmp = str;
     if ( option == HtmlOption::Strip ) {
-      stripHtml( tmp );
+      str = stripHtml( str );
     }
-    return QTextDocumentFragment::fromHtml( tmp.trimmed() ).toPlainText();
+    return QTextDocumentFragment::fromHtml( str.trimmed() ).toPlainText();
   }
   return str;
 }
diff --git a/src/common/htmlescape.hh b/src/common/htmlescape.hh
index 0c3442bde..e437cde15 100644
--- a/src/common/htmlescape.hh
+++ b/src/common/htmlescape.hh
@@ -25,9 +25,9 @@ string preformat( string const &, bool baseRightToLeft = false );
 
 // Escapes the given string to be included in JavaScript.
 string escapeForJavaScript( string const & );
-QString stripHtml( QString & tmp );
+QString stripHtml( QString tmp );
 // Replace html entities
-QString unescape( QString const & str, HtmlOption option = HtmlOption::Strip );
+QString unescape( QString str, HtmlOption option = HtmlOption::Strip );
 
 QString fromHtmlEscaped( QString const & str );
 string unescapeUtf8( string const & str, HtmlOption option = HtmlOption::Strip );
diff --git a/src/dict/stardict.cc b/src/dict/stardict.cc
index 468626413..6a4b0f3c0 100644
--- a/src/dict/stardict.cc
+++ b/src/dict/stardict.cc
@@ -422,10 +422,12 @@ class PowerWordDataProcessor
       }
       old = s;
     }
-    s.replace( QRegularExpression( "&.\\s*\\{",
-                                   QRegularExpression::UseUnicodePropertiesOption
-                                     | QRegularExpression::DotMatchesEverythingOption ),
-               "" );
+
+    static QRegularExpression leadingBrace( "&.\\s*\\{",
+                                            QRegularExpression::UseUnicodePropertiesOption
+                                              | QRegularExpression::DotMatchesEverythingOption );
+
+    s.replace( leadingBrace, "" );
     s.replace( "}", "" );
   }
 
@@ -448,18 +450,18 @@ string StardictDictionary::handleResource( char type, char const * resource, siz
     {
       QString articleText = QString( "<div class=\"sdct_h\">" ) + QString::fromUtf8( resource, size ) + "</div>";
 
-      QRegularExpression imgRe( R"((<\s*(?:img|script)\s+[^>]*src\s*=\s*["']?)(?!(?:data|https?|ftp):))",
-                                QRegularExpression::CaseInsensitiveOption );
-      QRegularExpression linkRe( R"((<\s*link\s+[^>]*href\s*=\s*["']?)(?!(?:data|https?|ftp):))",
-                                 QRegularExpression::CaseInsensitiveOption );
+      static QRegularExpression imgRe( R"((<\s*(?:img|script)\s+[^>]*src\s*=\s*["']?)(?!(?:data|https?|ftp):))",
+                                       QRegularExpression::CaseInsensitiveOption );
+      static QRegularExpression linkRe( R"((<\s*link\s+[^>]*href\s*=\s*["']?)(?!(?:data|https?|ftp):))",
+                                        QRegularExpression::CaseInsensitiveOption );
 
       articleText.replace( imgRe, "\\1bres://" + QString::fromStdString( getId() ) + "/" )
         .replace( linkRe, "\\1bres://" + QString::fromStdString( getId() ) + "/" );
 
       // Handle links to articles
 
-      QRegularExpression linksReg( R"(<a(\s*[^>]*)href\s*=\s*['"](bword://)?([^'"]+)['"])",
-                                   QRegularExpression::CaseInsensitiveOption );
+      static QRegularExpression linksReg( R"(<a(\s*[^>]*)href\s*=\s*['"](bword://)?([^'"]+)['"])",
+                                          QRegularExpression::CaseInsensitiveOption );
 
 
       int pos = 0;
@@ -508,9 +510,9 @@ string StardictDictionary::handleResource( char type, char const * resource, siz
 
       // Handle "audio" tags
 
-      QRegularExpression audioRe( R"(<\s*audio\s*src\s*=\s*(["']+)([^"']+)(["'])\s*>(.*)</audio>)",
-                                  QRegularExpression::CaseInsensitiveOption
-                                    | QRegularExpression::DotMatchesEverythingOption );
+      static QRegularExpression audioRe( R"(<\s*audio\s*src\s*=\s*(["']+)([^"']+)(["'])\s*>(.*)</audio>)",
+                                         QRegularExpression::CaseInsensitiveOption
+                                           | QRegularExpression::DotMatchesEverythingOption );
 
 
       pos = 0;
@@ -523,20 +525,19 @@ string StardictDictionary::handleResource( char type, char const * resource, siz
 
         QString src = match.captured( 2 );
 
-        if ( src.indexOf( "://" ) >= 0 )
+        if ( src.indexOf( "://" ) >= 0 ) {
           articleNewText += match.captured();
-
+        }
         else {
-          std::string href = "\"gdau://" + getId() + "/" + src.toUtf8().data() + "\"";
-          QString newTag   = QString::fromUtf8(
-            ( addAudioLink( href, getId() ) + "<span class=\"sdict_h_wav\"><a href=" + href + ">" ).c_str() );
-          newTag += match.captured( 4 );
-          if ( match.captured( 4 ).indexOf( "<img " ) < 0 )
-
+          std::string href   = "\"gdau://" + getId() + "/" + src.toUtf8().data() + "\"";
+          std::string newTag = addAudioLink( href, getId() ) + "<span class=\"sdict_h_wav\"><a href=" + href + ">";
+          newTag += match.captured( 4 ).toUtf8().constData();
+          if ( match.captured( 4 ).indexOf( "<img " ) < 0 ) {
             newTag += R"( <img src="qrc:///icons/playsound.png" border="0" alt="Play">)";
+          }
           newTag += "</a></span>";
 
-          articleNewText += newTag;
+          articleNewText += QString::fromStdString( newTag );
         }
       }
       if ( pos ) {
@@ -544,8 +545,8 @@ string StardictDictionary::handleResource( char type, char const * resource, siz
         articleText = articleNewText;
         articleNewText.clear();
       }
-
-      return ( articleText.toUtf8().data() );
+      auto text = articleText.toUtf8();
+      return text.data();
     }
     case 'm': // Pure meaning, usually means preformatted text
       return "<div class=\"sdct_m\">" + Html::preformat( string( resource, size ), isToLanguageRTL() ) + "</div>";
@@ -614,8 +615,8 @@ void StardictDictionary::pangoToHtml( QString & text )
  * Attributes "fallback", "lang", "gravity", "gravity_hint" just ignored
  */
 
-  QRegularExpression spanRegex( "<span\\s*([^>]*)>", QRegularExpression::CaseInsensitiveOption );
-  QRegularExpression styleRegex( "(\\w+)=\"([^\"]*)\"" );
+  static QRegularExpression spanRegex( "<span\\s*([^>]*)>", QRegularExpression::CaseInsensitiveOption );
+  static QRegularExpression styleRegex( "(\\w+)=\"([^\"]*)\"" );
 
   text.replace( "\n", "<br>" );
 
@@ -1554,7 +1555,8 @@ void StardictResourceRequest::run()
       QString id = QString::fromUtf8( dict.getId().c_str() );
       int pos    = 0;
 
-      QRegularExpression links( R"(url\(\s*(['"]?)([^'"]*)(['"]?)\s*\))", QRegularExpression::CaseInsensitiveOption );
+      static QRegularExpression links( R"(url\(\s*(['"]?)([^'"]*)(['"]?)\s*\))",
+                                       QRegularExpression::CaseInsensitiveOption );
 
       QString newCSS;
       QRegularExpressionMatchIterator it = links.globalMatch( css );
diff --git a/src/ui/articleview.cc b/src/ui/articleview.cc
index 3c6d306ad..d66ab8397 100644
--- a/src/ui/articleview.cc
+++ b/src/ui/articleview.cc
@@ -137,7 +137,7 @@ ArticleView::ArticleView( QWidget * parent,
   connect( searchPanel->previous, &QPushButton::clicked, this, &ArticleView::on_searchPrevious_clicked );
   connect( searchPanel->next, &QPushButton::clicked, this, &ArticleView::on_searchNext_clicked );
   connect( searchPanel->close, &QPushButton::clicked, this, &ArticleView::on_searchCloseButton_clicked );
-  connect( searchPanel->caseSensitive, &QPushButton::clicked, this, &ArticleView::on_searchCaseSensitive_clicked );
+  connect( searchPanel->caseSensitive, &QCheckBox::toggled, this, &ArticleView::on_searchCaseSensitive_clicked );
   connect( searchPanel->lineEdit, &QLineEdit::textEdited, this, &ArticleView::on_searchText_textEdited );
   connect( searchPanel->lineEdit, &QLineEdit::returnPressed, this, &ArticleView::on_searchText_returnPressed );
   connect( ftsSearchPanel->next, &QPushButton::clicked, this, &ArticleView::on_ftsSearchNext_clicked );
@@ -1963,8 +1963,11 @@ void ArticleView::on_searchCloseButton_clicked()
   closeSearch();
 }
 
-void ArticleView::on_searchCaseSensitive_clicked()
+void ArticleView::on_searchCaseSensitive_clicked( bool checked )
 {
+  //clear the previous findText results.
+  //when the results is empty, the highlight has not been removed.more likely a qt bug.
+  webview->findText( "" );
   performFindOperation( false );
 }
 
@@ -2027,11 +2030,6 @@ void ArticleView::performFindOperation( bool backwards )
 
   findText( text, f, [ text, this ]( bool match ) {
     bool nomatch = !text.isEmpty() && !match;
-    if ( nomatch ) {
-      //clear the previous findText results.
-      //when the results is empty, the highlight has not been removed.more likely a qt bug.
-      webview->findText( "" );
-    }
     Utils::Widget::setNoResultColor( searchPanel->lineEdit, nomatch );
   } );
 }
diff --git a/src/ui/articleview.hh b/src/ui/articleview.hh
index 36b6b20b0..2aa82f8f0 100644
--- a/src/ui/articleview.hh
+++ b/src/ui/articleview.hh
@@ -357,7 +357,7 @@ private slots:
   void on_searchText_textEdited();
   void on_searchText_returnPressed();
   void on_searchCloseButton_clicked();
-  void on_searchCaseSensitive_clicked();
+  void on_searchCaseSensitive_clicked( bool );
 
   void on_ftsSearchPrevious_clicked();
   void on_ftsSearchNext_clicked();