diff --git a/src/models/highlightedtext.cpp b/src/models/highlightedtext.cpp
index 21e606a8..9b4dfd61 100644
--- a/src/models/highlightedtext.cpp
+++ b/src/models/highlightedtext.cpp
@@ -27,6 +27,8 @@
 
 #include "formattingutils.h"
 
+using LineFormat = QVector<QTextLayout::FormatRange>;
+
 #if KFSyntaxHighlighting_FOUND
 // highlighter using KSyntaxHighlighting
 class HighlightingImplementation : public KSyntaxHighlighting::AbstractHighlighter
@@ -38,13 +40,23 @@ class HighlightingImplementation : public KSyntaxHighlighting::AbstractHighlight
     }
     ~HighlightingImplementation() override = default;
 
-    virtual QVector<QTextLayout::FormatRange> format(const QString& text)
+    void formatText(const QStringList& text)
     {
+        if (m_lines != text) {
+            m_lines = text;
+        }
+
         m_formats.clear();
+        m_state = {};
 
-        highlightLine(text, {});
+        for (const auto& line : text) {
+            m_formats.push_back(formatLine(line));
+        }
+    }
 
-        return m_formats;
+    virtual LineFormat format(int lineIndex) const
+    {
+        return m_formats.at(lineIndex);
     }
 
     virtual void themeChanged()
@@ -66,6 +78,7 @@ class HighlightingImplementation : public KSyntaxHighlighting::AbstractHighlight
     virtual void setHighlightingDefinition(const KSyntaxHighlighting::Definition& definition)
     {
         setDefinition(definition);
+        formatText(m_lines);
     }
 
     virtual QString definitionName() const
@@ -73,30 +86,49 @@ class HighlightingImplementation : public KSyntaxHighlighting::AbstractHighlight
         return definition().name();
     }
 
+    virtual LineFormat formatLine(const QString& line)
+    {
+        m_lineFormat.clear();
+        m_state = highlightLine(line, m_state);
+        return m_lineFormat;
+    }
+
 protected:
     void applyFormat(int offset, int length, const KSyntaxHighlighting::Format& format) override
     {
         QTextCharFormat textCharFormat;
         textCharFormat.setForeground(format.textColor(theme()));
         textCharFormat.setFontWeight(format.isBold(theme()) ? QFont::Bold : QFont::Normal);
-        m_formats.push_back({offset, length, textCharFormat});
+        m_lineFormat.push_back({offset, length, textCharFormat});
     }
 
 private:
     KSyntaxHighlighting::Repository* m_repository;
-    QVector<QTextLayout::FormatRange> m_formats;
+    KSyntaxHighlighting::State m_state;
+    QStringList m_lines; // for reformatting if definition changes
+    LineFormat m_lineFormat;
+    QVector<LineFormat> m_formats;
 };
 #else
-// stub incase KSyntaxHighlighting is not available
+// stub in case KSyntaxHighlighting is not available
 class HighlightingImplementation
 {
 public:
     HighlightingImplementation(KSyntaxHighlighting::Repository* /*repository*/) { }
     virtual ~HighlightingImplementation() = default;
 
-    virtual QVector<QTextLayout::FormatRange> format(const QString& /*text*/)
+    void formatText(const QStringList& text)
     {
-        return {};
+        m_formats.clear();
+
+        for (const auto& line : text) {
+            m_formats.push_back(formatLine(line));
+        }
+    }
+
+    LineFormat format(int lineIndex) const
+    {
+        return m_formats.at(lineIndex);
     }
 
     virtual void themeChanged() { }
@@ -105,7 +137,17 @@ class HighlightingImplementation
     virtual QString definitionName() const
     {
         return {};
+    };
+
+private:
+    // stub implementation necessary for testing
+    virtual LineFormat formatLine(const QString& line)
+    {
+        return {{QTextLayout::FormatRange {0, line.length(), {}}}};
     }
+
+    Q_DISABLE_COPY(HighlightingImplementation)
+    QVector<LineFormat> m_formats;
 };
 #endif
 
@@ -118,7 +160,19 @@ class AnsiHighlightingImplementation : public HighlightingImplementation
     }
     ~AnsiHighlightingImplementation() override = default;
 
-    QVector<QTextLayout::FormatRange> format(const QString& text) final
+    void themeChanged() override
+    {
+        m_colorScheme = KColorScheme(QPalette::Normal, KColorScheme::Complementary);
+    }
+
+    void setHighlightingDefinition(const KSyntaxHighlighting::Definition& /*definition*/) override { }
+    QString definitionName() const override
+    {
+        return {};
+    }
+
+private:
+    LineFormat formatLine(const QString& text) override
     {
         QVector<QTextLayout::FormatRange> formats;
 
@@ -167,18 +221,6 @@ class AnsiHighlightingImplementation : public HighlightingImplementation
         return formats;
     }
 
-    void themeChanged() override
-    {
-        m_colorScheme = KColorScheme(QPalette::Normal, KColorScheme::Complementary);
-    }
-
-    void setHighlightingDefinition(const KSyntaxHighlighting::Definition& /*definition*/) override { }
-    QString definitionName() const override
-    {
-        return {};
-    }
-
-private:
     KColorScheme m_colorScheme;
 };
 
@@ -186,9 +228,10 @@ class AnsiHighlightingImplementation : public HighlightingImplementation
 class HighlightedLine
 {
 public:
-    HighlightedLine(HighlightingImplementation* highlighter, QString text)
+    HighlightedLine(HighlightingImplementation* highlighter, const QString& text, int index)
         : m_highlighter(highlighter)
-        , m_text(std::move(text))
+        , m_text(Util::removeAnsi(text))
+        , m_index(index)
         , m_layout(nullptr)
     {
     }
@@ -216,12 +259,10 @@ class HighlightedLine
         if (!m_layout) {
             m_layout = std::make_unique<QTextLayout>();
             m_layout->setFont(QFontDatabase::systemFont(QFontDatabase::FixedFont));
-            const auto& ansiFreeLine = Util::removeAnsi(m_text);
-            m_layout->setText(ansiFreeLine);
+            m_layout->setText(m_text);
         }
 
-        m_layout->setFormats(m_highlighter->format(m_text));
-
+        m_layout->setFormats(m_highlighter->format(m_index));
         m_layout->beginLayout();
 
         // there is at most one line, so we don't need to check this multiple times
@@ -234,6 +275,7 @@ class HighlightedLine
 
     HighlightingImplementation* m_highlighter;
     QString m_text;
+    int m_index;
     std::unique_ptr<QTextLayout> m_layout;
 };
 
@@ -241,6 +283,7 @@ HighlightedText::HighlightedText(KSyntaxHighlighting::Repository* repository, QO
     : QObject(parent)
     , m_repository(repository)
 {
+    Q_UNUSED(repository);
 }
 
 HighlightedText::~HighlightedText() = default;
@@ -262,9 +305,12 @@ void HighlightedText::setText(const QStringList& text)
     }
 
     m_highlightedLines.reserve(text.size());
-    std::transform(text.cbegin(), text.cend(), std::back_inserter(m_highlightedLines), [this](const QString& text) {
-        return HighlightedLine {m_highlighter.get(), text};
-    });
+    m_highlighter->formatText(text);
+    int index = 0;
+    std::transform(text.cbegin(), text.cend(), std::back_inserter(m_highlightedLines),
+                   [this, &index](const QString& text) {
+                       return HighlightedLine {m_highlighter.get(), text, index++};
+                   });
 
     connect(this, &HighlightedText::definitionChanged, this, &HighlightedText::updateHighlighting);