diff --git a/src/xlsxworkbook.cpp b/src/xlsxworkbook.cpp
index db2416d..478fadf 100755
--- a/src/xlsxworkbook.cpp
+++ b/src/xlsxworkbook.cpp
@@ -44,7 +44,6 @@ Workbook::Workbook(QObject *parent) :
     m_window_width = 16095;
     m_window_height = 9660;
 
-    m_optimization_enabled = false;
     m_strings_to_numbers_enabled = false;
     m_activesheet = 0;
     m_firstsheet = 0;
@@ -78,33 +77,6 @@ void Workbook::save(const QString &name)
     package.createPackage(name);
 }
 
-/*!
-  Reduces the amount of data stored in memory so
-  that large files can be written efficiently
-
-  Note, in this mode a row of data is written and
-  then discarded when a cell in a new row is added
-  via one of the worksheet write_() methods. As such
-  data should be written in sequential row order once
-  this mode is on.
-
-  It is used to optimise speed and reduce memory usage.
-  However, these design goals meant that it wasn't easy
-  to implement features that many users requested such as
-  writing formatting and data separately.
-
-  This feature is disabled by default.
- */
-void Workbook::setOptimizationEnabled(bool enable)
-{
-    m_optimization_enabled = enable;
-}
-
-bool Workbook::isOptimizationEnabled() const
-{
-    return m_optimization_enabled;
-}
-
 /*
   Enable the worksheet.write() method to convert strings
   to numbers, where possible, using float() in order to avoid
diff --git a/src/xlsxworkbook.h b/src/xlsxworkbook.h
index 51bfb35..d84d064 100755
--- a/src/xlsxworkbook.h
+++ b/src/xlsxworkbook.h
@@ -48,7 +48,6 @@ public:
     Format *addFormat();
 //    void addChart();
     void defineName(const QString &name, const QString &formula);
-    void setOptimizationEnabled(bool enable=true);
     void setStringsToNumbersEnabled(bool enable=true);
 
     void save(const QString &name);
@@ -60,14 +59,12 @@ private:
     QList<Worksheet *> worksheets() const;
     SharedStrings *sharedStrings();
     Styles *styles();
-    bool isOptimizationEnabled() const;
     bool isStringsToNumbersEnabled() const;
     void saveToXmlFile(QIODevice *device);
 
     SharedStrings *m_sharedStrings;
     QList<Worksheet *> m_worksheets;
     Styles *m_styles;
-    bool m_optimization_enabled; //constant_memory
     bool m_strings_to_numbers_enabled;
 
     int m_x_window;
diff --git a/src/xlsxworksheet.cpp b/src/xlsxworksheet.cpp
index cde55b8..c4a80be 100755
--- a/src/xlsxworksheet.cpp
+++ b/src/xlsxworksheet.cpp
@@ -247,13 +247,6 @@ int Worksheet::checkDimensions(int row, int col, bool ignore_row, bool ignore_co
     if (row >= m_xls_rowmax || col >= m_xls_colmax)
         return -1;
 
-//    // In optimization mode we don't change dimensions for rows
-//    // that are already written.
-//    if (!ignore_row && !ignore_col && m_optimization == 1) {
-//        if (row < m_previous_row)
-//            return -1;
-//    }
-
     if (!ignore_row) {
         if (row < m_dim_rowmin) m_dim_rowmin = row;
         if (row > m_dim_rowmax) m_dim_rowmax = row;