diff --git a/Makefile b/Makefile
index 928bb596a7ba2d83fb31628a1fe0ce0dd5192b78..f632e6ed188e180fe79f0ccdb42d037fe29fb751 100644
--- a/Makefile
+++ b/Makefile
@@ -36,8 +36,8 @@ OPT += -DWRITE_IMAGE
 OPT += -DPHASE_ON
 # Support CFITSIO
 OPT += -DFITSIO
-# Perform true parallel fits writing
-OPT += -DPARALLELIO
+# Perform true parallel images writing
+#OPT += -DPARALLELIO
 
 ifeq (FITSIO,$(findstring FITSIO,$(OPT)))
 	LIBS += -L$(FITSIO_LIB) -lcfitsio
diff --git a/w-stacking-fftw.c b/w-stacking-fftw.c
index 93e520d72090bc6abe5120b87aa50ac756fadbb0..55244baa73b6378fde3c111568963353bc33ee24 100644
--- a/w-stacking-fftw.c
+++ b/w-stacking-fftw.c
@@ -104,8 +104,8 @@ int main(int argc, char * argv[])
 	double resolution;
 
         // Mesh related parameters: global size
-	int grid_size_x = 4096;
-	int grid_size_y = 4096;
+	int grid_size_x = 2048;
+	int grid_size_y = 2048;
 	// Split Mesh size (auto-calculated)
 	int local_grid_size_x;
 	int local_grid_size_y;