diff --git a/CMakeLists.txt b/CMakeLists.txt
index c2b7cb7673..6e29be2145 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -54,7 +54,6 @@ include_directories(BEFORE
     ${CMAKE_CURRENT_SOURCE_DIR}/libkdecorations
     ${CMAKE_CURRENT_SOURCE_DIR}/effects
     ${CMAKE_CURRENT_SOURCE_DIR}/tabbox
-    ${KDEBASE_WORKSPACE_SOURCE_DIR}/libs/kworkspace
     )
 
 add_subdirectory( libkdecorations )
@@ -173,7 +172,7 @@ qt4_add_dbus_interface( kwin_KDEINIT_SRCS
 
 qt4_add_resources( kwin_KDEINIT_SRCS resources.qrc )
 
-set(kwinLibs ${KDE4_KDEUI_LIBS} ${KDE4_PLASMA_LIBS} ${QT_QTDECLARATIVE_LIBRARY} kdeclarative kworkspace kdecorations kwineffects ${X11_LIBRARIES} ${X11_Xrandr_LIB} ${X11_Xcomposite_LIB} ${X11_Xdamage_LIB} ${X11_Xrender_LIB} ${X11_Xfixes_LIB})
+set(kwinLibs ${KDE4_KDEUI_LIBS} ${KDE4_PLASMA_LIBS} ${QT_QTDECLARATIVE_LIBRARY} kdeclarative kdecorations kwineffects ${X11_LIBRARIES} ${X11_Xrandr_LIB} ${X11_Xcomposite_LIB} ${X11_Xdamage_LIB} ${X11_Xrender_LIB} ${X11_Xfixes_LIB})
 
 find_library(XF86VM_LIBRARY Xxf86vm)
 if (XF86VM_LIBRARY)
diff --git a/main.cpp b/main.cpp
index 06738a8504..7ad973208a 100644
--- a/main.cpp
+++ b/main.cpp
@@ -53,7 +53,16 @@ along with this program.  If not, see <http://www.gnu.org/licenses/>.
 #include <QLabel>
 #include <KComboBox>
 #include <QVBoxLayout>
-#include <kworkspace/kworkspace.h>
+
+#include "config-workspace.h"
+
+#ifdef HAVE_UNISTD_H
+#include <unistd.h>
+#endif // HAVE_UNISTD_H
+
+#ifdef HAVE_MALLOC_H
+#include <malloc.h>
+#endif // HAVE_MALLOC_H
 
 #include <ksmserver_interface.h>
 
@@ -407,7 +416,20 @@ KDE_EXPORT int kdemain(int argc, char * argv[])
         }
     }
 
-    KWorkSpace::trimMalloc();
+#ifdef M_TRIM_THRESHOLD
+    // Prevent fragmentation of the heap by malloc (glibc).
+    //
+    // The default threshold is 128*1024, which can result in a large memory usage
+    // due to fragmentation especially if we use the raster graphicssystem. On the
+    // otherside if the threshold is too low, free() starts to permanently ask the kernel
+    // about shrinking the heap.
+#ifdef HAVE_UNISTD_H
+    const int pagesize = sysconf(_SC_PAGESIZE);
+#else
+    const int pagesize = 4*1024;
+#endif // HAVE_UNISTD_H
+    mallopt(M_TRIM_THRESHOLD, 5*pagesize);
+#endif // M_TRIM_THRESHOLD
 
     // the raster graphicssystem has a quite terrible performance on the XRender backend or when not
     // compositing at all while some to many decorations suffer from bad performance of the native