larger allocation chunks

libs/core/pxtcore.h

@@ -14,9 +14,15 @@ void debuglog(const char *format, ...);
 #define xmalloc malloc
 #define xfree free
 
-#define GC_MAX_ALLOC_SIZE 9000
 
+#if CONFIG_ENABLED(MICROBIT_BLE_ENABLED) // ble mode
+#define GC_MAX_ALLOC_SIZE 4000
 #define GC_BLOCK_SIZE 256
+#else // radio mode
+#define GC_MAX_ALLOC_SIZE 9000
+#define GC_BLOCK_SIZE 1024 // radio mode
+#endif
+
 #define NON_GC_HEAP_RESERVATION 1024
 
 #define DMESG NOLOG