Performance|Client: Faster resizing of the view

When the view grid was updated, LensFX was always releasing all GL
resources for all viewports even if the viewports were only resized.

doomsday/client/src/render/viewports.cpp

@@ -345,16 +345,21 @@ void R_UpdateViewPortGeometry(viewport_t *port, int col, int row)
 
 bool R_SetViewGrid(int numCols, int numRows)
 {
-    // LensFx needs to reallocate resources only for the consoles in use.
-    LensFx_GLRelease();
-
     if(numCols > 0 && numRows > 0)
     {
         if(numCols * numRows > DDMAXPLAYERS)
         {
             return false;
         }
 
+        if(numCols != gridCols || numRows != gridRows)
+        {
+            // The number of consoles has changes; LensFx needs to reallocate resources
+            // only for the consoles in use.
+            /// @todo This could be done smarter, only for the affected viewports. -jk
+            LensFx_GLRelease();
+        }
+
         if(numCols > DDMAXPLAYERS)
             numCols = DDMAXPLAYERS;
         if(numRows > DDMAXPLAYERS)