diff --git a/src/lib/htmlhighlighter.cpp b/src/lib/htmlhighlighter.cpp
--- a/src/lib/htmlhighlighter.cpp
+++ b/src/lib/htmlhighlighter.cpp
@@ -1,5 +1,6 @@
 /*
     Copyright (C) 2016 Volker Krause <vkrause@kde.org>
+    Copyright (C) 2018 Christoph Cullmann <cullmann@kde.org>
 
     Permission is hereby granted, free of charge, to any person obtaining
     a copy of this software and associated documentation files (the
@@ -32,6 +33,7 @@
 #include <QFile>
 #include <QFileInfo>
 #include <QTextStream>
+#include <QVarLengthArray>
 
 using namespace KSyntaxHighlighting;
 
@@ -114,25 +116,32 @@
     if (length == 0)
         return;
 
-    if (!format.isDefaultTextStyle(theme())) {
+    // collect potential output, cheaper than thinking about "is there any?"
+    QVarLengthArray<QString, 16> formatOutput;
+    if (format.hasTextColor(theme()))
+        formatOutput << QStringLiteral("color:") << format.textColor(theme()).name() << QStringLiteral(";");
+    if (format.hasBackgroundColor(theme()))
+        formatOutput << QStringLiteral("background-color:") << format.backgroundColor(theme()).name() << QStringLiteral(";");
+    if (format.isBold(theme()))
+        formatOutput << QStringLiteral("font-weight:bold;");
+    if (format.isItalic(theme()))
+        formatOutput << QStringLiteral("font-style:italic;");
+    if (format.isUnderline(theme()))
+        formatOutput << QStringLiteral("text-decoration:underline;");
+    if (format.isStrikeThrough(theme()))
+        formatOutput << QStringLiteral("text-decoration:line-through;");
+
+    if (!formatOutput.isEmpty()) {
         *d->out << "<span style=\"";
-        if (format.hasTextColor(theme()))
-            *d->out << "color:" << format.textColor(theme()).name() << ";";
-        if (format.hasBackgroundColor(theme()))
-            *d->out << "background-color:" << format.backgroundColor(theme()).name() << ";";
-        if (format.isBold(theme()))
-            *d->out << "font-weight:bold;";
-        if (format.isItalic(theme()))
-            *d->out << "font-style:italic;";
-        if (format.isUnderline(theme()))
-            *d->out << "text-decoration:underline;";
-        if (format.isStrikeThrough(theme()))
-            *d->out << "text-decoration:line-through;";
+        for (const auto &out : qAsConst(formatOutput)) {
+            *d->out << out;
+        }
         *d->out << "\">";
     }
 
     *d->out << d->currentLine.mid(offset, length).toHtmlEscaped();
 
-    if (!format.isDefaultTextStyle(theme()))
+    if (!formatOutput.isEmpty()) {
         *d->out << "</span>";
+    }
 }
diff --git a/src/lib/rule.cpp b/src/lib/rule.cpp
--- a/src/lib/rule.cpp
+++ b/src/lib/rule.cpp
@@ -1,5 +1,6 @@
 /*
     Copyright (C) 2016 Volker Krause <vkrause@kde.org>
+    Copyright (C) 2018 Christoph Cullmann <cullmann@kde.org>
 
     Permission is hereby granted, free of charge, to any person obtaining
     a copy of this software and associated documentation files (the
@@ -99,6 +100,9 @@
 void Rule::setDefinition(const Definition &def)
 {
     m_def = def;
+
+    // cache for DefinitionData::wordDelimiters, is accessed VERY often
+    m_wordDelimiter = &DefinitionData::get(m_def.definition())->wordDelimiters;
 }
 
 QString Rule::attribute() const
@@ -273,8 +277,8 @@
 
 bool Rule::isWordDelimiter(QChar c) const
 {
-    auto defData = DefinitionData::get(m_def.definition());
-    return defData->isWordDelimiter(c);
+    // perf tells contains is MUCH faster than binary search here, very short array
+    return m_wordDelimiter.contains(c);
 }
 
 
@@ -569,7 +573,9 @@
         if (m_keywordList.contains(text.midRef(offset, newOffset - offset)))
             return newOffset;
     }
-    return offset;
+
+    // we don't match, but we can skip until newOffset as we can't start a keyword in-between
+    return MatchResult(offset, newOffset);
 }
 
 
diff --git a/src/lib/rule_p.h b/src/lib/rule_p.h
--- a/src/lib/rule_p.h
+++ b/src/lib/rule_p.h
@@ -88,6 +88,9 @@
     bool m_firstNonSpace = false;
     bool m_lookAhead = false;
     bool m_dynamic = false;
+
+    // cache for DefinitionData::wordDelimiters, is accessed VERY often
+    QStringRef m_wordDelimiter;
 };