diff --git a/lanczos-fragment.glsl b/lanczos-fragment.glsl
index 639bf847b4..1aabdb8bc8 100644
--- a/lanczos-fragment.glsl
+++ b/lanczos-fragment.glsl
@@ -1,12 +1,11 @@
 uniform sampler2D texUnit;
 uniform vec2 offsets[25];
 uniform vec4 kernel[25];
-uniform int kernelSize;
 
 void main(void)
 {
     vec4 sum = texture2D(texUnit, gl_TexCoord[0].st) * kernel[0];
-    for (int i = 1; i < kernelSize; i++) {
+    for (int i = 1; i < 25; i++) {
         sum += texture2D(texUnit, gl_TexCoord[0].st - offsets[i]) * kernel[i];
         sum += texture2D(texUnit, gl_TexCoord[0].st + offsets[i]) * kernel[i];
     }
diff --git a/lanczosfilter.cpp b/lanczosfilter.cpp
index 3d450383e2..a74cd76020 100644
--- a/lanczosfilter.cpp
+++ b/lanczosfilter.cpp
@@ -78,7 +78,6 @@ void LanczosFilter::init()
             {
             m_shader->bind();
             m_uTexUnit    = m_shader->uniformLocation("texUnit");
-            m_uKernelSize = m_shader->uniformLocation("kernelSize");
             m_uKernel     = m_shader->uniformLocation("kernel");
             m_uOffsets    = m_shader->uniformLocation("offsets");
             m_shader->unbind();
@@ -134,7 +133,7 @@ static float lanczos( float x, float a )
     return sinc( x ) * sinc( x / a );
     }
 
-QVector<QVector4D> LanczosFilter::createKernel( float delta )
+void LanczosFilter::createKernel( float delta, int *size )
     {
     const float a = 2.0;
 
@@ -146,7 +145,6 @@ QVector<QVector4D> LanczosFilter::createKernel( float delta )
     const float factor = 1.0 / delta;
 
     QVector<float> values( kernelSize );
-    QVector<QVector4D> kernel( kernelSize );
     float sum = 0;
 
     for ( int i = 0; i < kernelSize; i++ ) {
@@ -155,23 +153,24 @@ QVector<QVector4D> LanczosFilter::createKernel( float delta )
         values[i] = val;
     }
 
+    memset(m_kernel, 0, 25 * sizeof(QVector4D));
+
     // Normalize the kernel
     for ( int i = 0; i < kernelSize; i++ ) {
         const float val = values[i] / sum;
-        kernel[i] = QVector4D( val, val, val, val );
+        m_kernel[i] = QVector4D( val, val, val, val );
     }
 
-    return kernel;
+    *size = kernelSize;
     }
 
-QVector<QVector2D> LanczosFilter::createOffsets( int count, float width, Qt::Orientation direction )
+void LanczosFilter::createOffsets( int count, float width, Qt::Orientation direction )
     {
-    QVector<QVector2D> offsets( count );
+    memset(m_offsets, 0, 25 * sizeof(QVector2D));
     for ( int i = 0; i < count; i++ ) {
-        offsets[i] = ( direction == Qt::Horizontal ) ?
+        m_offsets[i] = ( direction == Qt::Horizontal ) ?
                 QVector2D( i / width, 0 ) : QVector2D( 0, i / width );
     }
-    return offsets;
     }
 
 void LanczosFilter::performPaint( EffectWindowImpl* w, int mask, QRegion region, WindowPaintData& data )
@@ -240,14 +239,14 @@ void LanczosFilter::performPaint( EffectWindowImpl* w, int mask, QRegion region,
 
             // Set up the shader for horizontal scaling
             float dx = sw / float(tw);
-            QVector<QVector4D> kernel = createKernel( dx );
-            QVector<QVector2D> offsets = createOffsets( kernel.size(), sw, Qt::Horizontal );
+            int kernelSize;
+            createKernel( dx, &kernelSize );
+            createOffsets( kernelSize, sw, Qt::Horizontal );
 
             m_shader->bind();
             glUniform1i( m_uTexUnit, 0 );
-            glUniform1i( m_uKernelSize, kernel.size() );
-            glUniform2fv( m_uOffsets, offsets.size(), (const GLfloat*)offsets.constData() );
-            glUniform4fv( m_uKernel, kernel.size(), (const GLfloat*)kernel.constData() );
+            glUniform2fv( m_uOffsets, 25, (const GLfloat*)m_offsets );
+            glUniform4fv( m_uKernel, 25, (const GLfloat*)m_kernel );
 
             // Draw the window back into the FBO, this time scaled horizontally
             glClear( GL_COLOR_BUFFER_BIT );
@@ -268,12 +267,11 @@ void LanczosFilter::performPaint( EffectWindowImpl* w, int mask, QRegion region,
 
             // Set up the shader for vertical scaling
             float dy = sh / float(th);
-            kernel = createKernel( dy );
-            offsets = createOffsets( kernel.size(), m_offscreenTex->height(), Qt::Vertical );
+            createKernel( dy, &kernelSize );
+            createOffsets( kernelSize, m_offscreenTex->height(), Qt::Vertical );
 
-            glUniform1i( m_uKernelSize, kernel.size() );
-            glUniform2fv( m_uOffsets, offsets.size(), (const GLfloat*)offsets.constData() );
-            glUniform4fv( m_uKernel, kernel.size(), (const GLfloat*)kernel.constData() );
+            glUniform2fv( m_uOffsets, 25, (const GLfloat*)m_offsets );
+            glUniform4fv( m_uKernel, 25, (const GLfloat*)m_kernel );
 
             float sx2 = tw / float(m_offscreenTex->width());
             float sy2 = 1 - (sh / float(m_offscreenTex->height()));
diff --git a/lanczosfilter.h b/lanczosfilter.h
index 8934c3c17f..9f9242545d 100644
--- a/lanczosfilter.h
+++ b/lanczosfilter.h
@@ -53,19 +53,20 @@ class LanczosFilter
     private:
         void init();
         void updateOffscreenSurfaces();
-        QVector<QVector4D> createKernel(float delta);
-        QVector<QVector2D> createOffsets(int count, float width, Qt::Orientation direction);
+        void createKernel(float delta, int *kernelSize);
+        void createOffsets(int count, float width, Qt::Orientation direction);
 #ifdef KWIN_HAVE_OPENGL_COMPOSITING
         GLTexture *m_offscreenTex;
         GLRenderTarget *m_offscreenTarget;
         GLShader *m_shader;
 #endif
         QBasicTimer m_timer;
+        QVector2D m_offsets[25];
+        QVector4D m_kernel[25];
         bool m_inited;
         int m_uTexUnit;
         int m_uOffsets;
         int m_uKernel;
-        int m_uKernelSize;
 };
 
 } // namespace