diff --git a/src/CCubes.c b/src/CCubes.c
index 0efc555..34af02d 100755
--- a/src/CCubes.c
+++ b/src/CCubes.c
@@ -205,7 +205,7 @@ SEXP CCubes(SEXP tt) {
     config_set_int("log", LOG_LEVEL_WARN);
     config_set_int("log:clccubes", LOG_LEVEL_DEBUG);
     config_set_int("log:ccubes", LOG_LEVEL_DEBUG);
-    config_set_int("log:cl", LOG_LEVEL_DEBUG);
+    config_set_int("log:cl", LOG_LEVEL_WARN);
 
     char log[100] = {0};
     sprintf(log, "log-ccubes");
@@ -357,6 +357,7 @@ SEXP CCubes(SEXP tt) {
 
                     // when needed, increase allocated memory
                     if (foundPI / estimPI > 0.9) {
+			ctx->rebuild = 1;
                         estimPI += 100000;
                         p_pichart =        R_Realloc(p_pichart,        posrows * estimPI,         int);
                         p_pichart_pos =    R_Realloc(p_pichart_pos,    pichart_words * estimPI,   unsigned int);
diff --git a/src/cl_setup.c b/src/cl_setup.c
index 3c77db7..8a2a3c1 100644
--- a/src/cl_setup.c
+++ b/src/cl_setup.c
@@ -21,7 +21,10 @@
 #include "logging.h"
 
 #include "cl_setup.h"
+
+#if 0
 #define CL_DEBUG
+#endif
 
 cl_int
 cl_init(struct cl_uctx *puctx)
diff --git a/src/clccubes.c b/src/clccubes.c
index b35bda5..90fa335 100755
--- a/src/clccubes.c
+++ b/src/clccubes.c
@@ -110,6 +110,7 @@ ccubes_create(const char *ccubes_kernel_file,
 			ccubes_kernel_file);
 		goto err;
 	}
+	ctx->rebuild = 1;
 
 	ctx->ninputs = ninputs;
 	ctx->posrows = posrows;
@@ -192,6 +193,14 @@ ccubes_build(struct ccubes_context *ctx)
 {
 	int rc = 0;
 
+	if (ctx->rebuild == 0)
+		return rc;
+
+	rc = ccubes_preprocess(ctx);
+	if (rc != 0) {
+		log_error("clccubes", "ccubes_preprocess failed (%d)", rc);
+		goto err;
+	}
 
 	rc = cl_build(*ctx->clctx, CL_DEVICE_TYPE_GPU,
 		ctx->ccubes_kernel_file, &ctx->ccubes_program);
@@ -207,6 +216,8 @@ ccubes_build(struct ccubes_context *ctx)
 		goto err;
 	}
 
+	ctx->rebuild = 0;
+
 err:
 	return rc;
 }
@@ -524,12 +535,6 @@ ccubes_do_tasks(struct ccubes_context *ccubesctx,
 		goto err;
 	}
 
-	rc = ccubes_preprocess(ccubesctx);
-	if (rc != 0) {
-		log_error("clccubes", "ccubes_preprocess failed (%d)", rc);
-		goto err;
-	}
-
 	rc = ccubes_build(ccubesctx);
 	if (rc != CL_SUCCESS) {
 		log_error("clccubes", "ccubes_build failed (%d)", rc);
diff --git a/src/clccubes.h b/src/clccubes.h
index b9b441e..38bce43 100755
--- a/src/clccubes.h
+++ b/src/clccubes.h
@@ -33,6 +33,7 @@
 struct ccubes_context {
 	struct cl_uctx *clctx;
 
+	int rebuild;
 	char *ccubes_kernel_file;
 	cl_program ccubes_program;
 	cl_kernel ccubes_task;