diff --git a/src/lib/rule.cpp b/src/lib/rule.cpp
--- a/src/lib/rule.cpp
+++ b/src/lib/rule.cpp
@@ -229,7 +229,7 @@
     return true;
 }
 
-MatchResult Rule::match(const QString &text, int offset, const QStringList &captures)
+MatchResult Rule::match(const QString &text, int offset, const QStringList &captures) const
 {
     Q_ASSERT(!text.isEmpty());
 
@@ -306,7 +306,7 @@
     return !m_chars.isEmpty();
 }
 
-MatchResult AnyChar::doMatch(const QString& text, int offset, const QStringList&)
+MatchResult AnyChar::doMatch(const QString& text, int offset, const QStringList&) const
 {
     if (m_chars.contains(text.at(offset)))
         return offset + 1;
@@ -326,7 +326,7 @@
     return true;
 }
 
-MatchResult DetectChar::doMatch(const QString& text, int offset, const QStringList &captures)
+MatchResult DetectChar::doMatch(const QString& text, int offset, const QStringList &captures) const
 {
     if (isDynamic()) {
         if (captures.size() <= m_captureIndex || captures.at(m_captureIndex).isEmpty())
@@ -353,7 +353,7 @@
     return true;
 }
 
-MatchResult Detect2Char::doMatch(const QString& text, int offset, const QStringList &captures)
+MatchResult Detect2Char::doMatch(const QString& text, int offset, const QStringList &captures) const
 {
     Q_UNUSED(captures); // TODO
     if (text.size() - offset < 2)
@@ -364,7 +364,7 @@
 }
 
 
-MatchResult DetectIdentifier::doMatch(const QString& text, int offset, const QStringList&)
+MatchResult DetectIdentifier::doMatch(const QString& text, int offset, const QStringList&) const
 {
     if (!text.at(offset).isLetter() && text.at(offset) != QLatin1Char('_'))
         return offset;
@@ -379,15 +379,15 @@
 }
 
 
-MatchResult DetectSpaces::doMatch(const QString& text, int offset, const QStringList&)
+MatchResult DetectSpaces::doMatch(const QString& text, int offset, const QStringList&) const
 {
     while(offset < text.size() && text.at(offset).isSpace())
         ++offset;
     return offset;
 }
 
 
-MatchResult Float::doMatch(const QString& text, int offset, const QStringList&)
+MatchResult Float::doMatch(const QString& text, int offset, const QStringList&) const
 {
     if (offset > 0 && !isWordDelimiter(text.at(offset - 1)))
         return offset;
@@ -425,7 +425,7 @@
 }
 
 
-MatchResult HlCChar::doMatch(const QString& text, int offset, const QStringList&)
+MatchResult HlCChar::doMatch(const QString& text, int offset, const QStringList&) const
 {
     if (text.size() < offset + 3)
         return offset;
@@ -450,7 +450,7 @@
 }
 
 
-MatchResult HlCHex::doMatch(const QString& text, int offset, const QStringList&)
+MatchResult HlCHex::doMatch(const QString& text, int offset, const QStringList&) const
 {
     if (offset > 0 && !isWordDelimiter(text.at(offset - 1)))
         return offset;
@@ -474,7 +474,7 @@
 }
 
 
-MatchResult HlCOct::doMatch(const QString& text, int offset, const QStringList&)
+MatchResult HlCOct::doMatch(const QString& text, int offset, const QStringList&) const
 {
     if (offset > 0 && !isWordDelimiter(text.at(offset - 1)))
         return offset;
@@ -496,7 +496,7 @@
 }
 
 
-MatchResult HlCStringChar::doMatch(const QString& text, int offset, const QStringList&)
+MatchResult HlCStringChar::doMatch(const QString& text, int offset, const QStringList&) const
 {
     return matchEscapedChar(text, offset);
 }
@@ -531,15 +531,15 @@
     return !m_contextName.isEmpty() || !m_defName.isEmpty();
 }
 
-MatchResult IncludeRules::doMatch(const QString& text, int offset, const QStringList&)
+MatchResult IncludeRules::doMatch(const QString& text, int offset, const QStringList&) const
 {
     Q_UNUSED(text);
     qCWarning(Log) << "Unresolved include rule for" << m_contextName << "##" << m_defName;
     return offset;
 }
 
 
-MatchResult Int::doMatch(const QString& text, int offset, const QStringList &captures)
+MatchResult Int::doMatch(const QString& text, int offset, const QStringList &captures) const
 {
     if (offset > 0 && !isWordDelimiter(text.at(offset - 1)))
         return offset;
@@ -564,7 +564,7 @@
     return !m_listName.isEmpty();
 }
 
-MatchResult KeywordListRule::doMatch(const QString& text, int offset, const QStringList&)
+MatchResult KeywordListRule::doMatch(const QString& text, int offset, const QStringList&) const
 {
     if (m_keywordList.isEmpty()) {
         const auto def = definition();
@@ -602,7 +602,7 @@
     return true;
 }
 
-MatchResult LineContinue::doMatch(const QString& text, int offset, const QStringList&)
+MatchResult LineContinue::doMatch(const QString& text, int offset, const QStringList&) const
 {
     if (offset == text.size() - 1 && text.at(offset) == m_char)
         return offset + 1;
@@ -621,7 +621,7 @@
     return true;
 }
 
-MatchResult RangeDetect::doMatch(const QString& text, int offset, const QStringList&)
+MatchResult RangeDetect::doMatch(const QString& text, int offset, const QStringList&) const
 {
     if (text.size() - offset < 2)
         return offset;
@@ -641,22 +641,31 @@
 {
     m_pattern = reader.attributes().value(QStringLiteral("String")).toString();
     m_regexp.setPattern(m_pattern);
+
     const auto isMinimal = Xml::attrToBool(reader.attributes().value(QStringLiteral("minimal")));
     const auto isCaseInsensitive = Xml::attrToBool(reader.attributes().value(QStringLiteral("insensitive")));
     m_regexp.setPatternOptions(
         (isMinimal ? QRegularExpression::InvertedGreedinessOption : QRegularExpression::NoPatternOption) |
         (isCaseInsensitive ? QRegularExpression::CaseInsensitiveOption : QRegularExpression::NoPatternOption));
-    return !m_pattern.isEmpty(); // m_regexp.isValid() would be better, but parses the regexp and thus is way too expensive
-}
 
-MatchResult RegExpr::doMatch(const QString& text, int offset, const QStringList &captures)
-{
+    // optimize the pattern for the non-dynamic case, we use them OFTEN
+    if (!isDynamic()) {
+        m_regexp.optimize();
+    }
+
+    // always using m_regexp.isValid() would be better, but parses the regexp and thus is way too expensive for release builds
     Q_ASSERT(m_regexp.isValid());
+    return !m_pattern.isEmpty();
+}
 
-    if (isDynamic())
-        m_regexp.setPattern(replaceCaptures(m_pattern, captures, true));
+MatchResult RegExpr::doMatch(const QString& text, int offset, const QStringList &captures) const
+{
+    /**
+     * for dynamic case: create new pattern with right instantiation
+     */
+    const auto &regexp = isDynamic() ? QRegularExpression(replaceCaptures(m_pattern, captures, true), m_regexp.patternOptions()) : m_regexp;
 
-    auto result = m_regexp.match(text, offset, QRegularExpression::NormalMatch, QRegularExpression::DontCheckSubjectStringMatchOption);
+    auto result = regexp.match(text, offset, QRegularExpression::NormalMatch, QRegularExpression::DontCheckSubjectStringMatchOption);
     if (result.capturedStart() == offset)
         return MatchResult(offset + result.capturedLength(), result.capturedTexts());
     return MatchResult(offset, result.capturedStart());
@@ -670,11 +679,13 @@
     return !m_string.isEmpty();
 }
 
-MatchResult StringDetect::doMatch(const QString& text, int offset, const QStringList &captures)
+MatchResult StringDetect::doMatch(const QString& text, int offset, const QStringList &captures) const
 {
-    auto pattern = m_string;
-    if (isDynamic())
-        pattern = replaceCaptures(m_string, captures, false);
+    /**
+     * for dynamic case: create new pattern with right instantiation
+     */
+    const auto &pattern = isDynamic() ? replaceCaptures(m_string, captures, false) : m_string;
+
     if (text.midRef(offset, pattern.size()).compare(pattern, m_caseSensitivity) == 0)
         return offset + pattern.size();
     return offset;
@@ -688,7 +699,7 @@
     return !m_word.isEmpty();
 }
 
-MatchResult WordDetect::doMatch(const QString& text, int offset, const QStringList &captures)
+MatchResult WordDetect::doMatch(const QString& text, int offset, const QStringList &captures) const
 {
     Q_UNUSED(captures); // TODO
     if (text.size() - offset < m_word.size())
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
@@ -71,13 +71,13 @@
     void resolveContext();
     void resolveAttributeFormat(Context *lookupContext);
 
-    MatchResult match(const QString &text, int offset, const QStringList &captures);
+    MatchResult match(const QString &text, int offset, const QStringList &captures) const;
 
     static Rule::Ptr create(const QStringRef &name);
 
 protected:
     virtual bool doLoad(QXmlStreamReader &reader);
-    virtual MatchResult doMatch(const QString &text, int offset, const QStringList &captures) = 0;
+    virtual MatchResult doMatch(const QString &text, int offset, const QStringList &captures) const = 0;
 
     bool isWordDelimiter(QChar c) const;
 
@@ -105,7 +105,7 @@
 {
 protected:
     bool doLoad(QXmlStreamReader & reader) override;
-    MatchResult doMatch(const QString & text, int offset, const QStringList&) override;
+    MatchResult doMatch(const QString & text, int offset, const QStringList&) const override;
 
 private:
     QString m_chars;
@@ -115,7 +115,7 @@
 {
 protected:
     bool doLoad(QXmlStreamReader & reader) override;
-    MatchResult doMatch(const QString & text, int offset, const QStringList &captures) override;
+    MatchResult doMatch(const QString & text, int offset, const QStringList &captures) const override;
 
 private:
     QChar m_char;
@@ -126,7 +126,7 @@
 {
 protected:
     bool doLoad(QXmlStreamReader & reader) override;
-    MatchResult doMatch(const QString & text, int offset, const QStringList &captures) override;
+    MatchResult doMatch(const QString & text, int offset, const QStringList &captures) const override;
 
 private:
     QChar m_char1;
@@ -136,19 +136,19 @@
 class DetectIdentifier : public Rule
 {
 protected:
-    MatchResult doMatch(const QString & text, int offset, const QStringList&) override;
+    MatchResult doMatch(const QString & text, int offset, const QStringList&) const override;
 };
 
 class DetectSpaces : public Rule
 {
 protected:
-    MatchResult doMatch(const QString & text, int offset, const QStringList&) override;
+    MatchResult doMatch(const QString & text, int offset, const QStringList&) const override;
 };
 
 class Float : public Rule
 {
 protected:
-    MatchResult doMatch(const QString & text, int offset, const QStringList&) override;
+    MatchResult doMatch(const QString & text, int offset, const QStringList&) const override;
 };
 
 class IncludeRules : public Rule
@@ -160,7 +160,7 @@
 
 protected:
     bool doLoad(QXmlStreamReader & reader) override;
-    MatchResult doMatch(const QString & text, int offset, const QStringList&) override;
+    MatchResult doMatch(const QString & text, int offset, const QStringList&) const override;
 
 private:
     QString m_contextName;
@@ -171,51 +171,51 @@
 class Int : public Rule
 {
 protected:
-    MatchResult doMatch(const QString & text, int offset, const QStringList &captures) override;
+    MatchResult doMatch(const QString & text, int offset, const QStringList &captures) const override;
 };
 
 class HlCChar : public Rule
 {
 protected:
-    MatchResult doMatch(const QString & text, int offset, const QStringList&) override;
+    MatchResult doMatch(const QString & text, int offset, const QStringList&) const override;
 };
 
 class HlCHex : public Rule
 {
 protected:
-    MatchResult doMatch(const QString & text, int offset, const QStringList&) override;
+    MatchResult doMatch(const QString & text, int offset, const QStringList&) const override;
 };
 
 class HlCOct : public Rule
 {
 protected:
-    MatchResult doMatch(const QString & text, int offset, const QStringList&) override;
+    MatchResult doMatch(const QString & text, int offset, const QStringList&) const override;
 };
 
 class HlCStringChar : public Rule
 {
 protected:
-    MatchResult doMatch(const QString & text, int offset, const QStringList&) override;
+    MatchResult doMatch(const QString & text, int offset, const QStringList&) const override;
 };
 
 class KeywordListRule : public Rule
 {
 protected:
     bool doLoad(QXmlStreamReader & reader) override;
-    MatchResult doMatch(const QString & text, int offset, const QStringList&) override;
+    MatchResult doMatch(const QString & text, int offset, const QStringList&) const override;
 
 private:
     QString m_listName;
-    KeywordList m_keywordList;
+    mutable KeywordList m_keywordList;
     bool m_hasCaseSensitivityOverride;
     Qt::CaseSensitivity m_caseSensitivityOverride;
 };
 
 class LineContinue : public Rule
 {
 protected:
     bool doLoad(QXmlStreamReader & reader) override;
-    MatchResult doMatch(const QString & text, int offset, const QStringList&) override;
+    MatchResult doMatch(const QString & text, int offset, const QStringList&) const override;
 
 private:
     QChar m_char;
@@ -225,7 +225,7 @@
 {
 protected:
     bool doLoad(QXmlStreamReader & reader) override;
-    MatchResult doMatch(const QString & text, int offset, const QStringList&) override;
+    MatchResult doMatch(const QString & text, int offset, const QStringList&) const override;
 
 private:
     QChar m_begin;
@@ -236,7 +236,7 @@
 {
 protected:
     bool doLoad(QXmlStreamReader & reader) override;
-    MatchResult doMatch(const QString & text, int offset, const QStringList &captures) override;
+    MatchResult doMatch(const QString & text, int offset, const QStringList &captures) const override;
 
 private:
     QString m_pattern;
@@ -247,7 +247,7 @@
 {
 protected:
     bool doLoad(QXmlStreamReader & reader) override;
-    MatchResult doMatch(const QString & text, int offset, const QStringList &captures) override;
+    MatchResult doMatch(const QString & text, int offset, const QStringList &captures) const override;
 
 private:
     QString m_string;
@@ -258,7 +258,7 @@
 {
 protected:
     bool doLoad(QXmlStreamReader & reader) override;
-    MatchResult doMatch(const QString & text, int offset, const QStringList &captures) override;
+    MatchResult doMatch(const QString & text, int offset, const QStringList &captures) const override;
 
 private:
     QString m_word;