Performance

- Removed Context::timer_sync, as it makes no sense now that sync is not an
  automatic operation like gc.

src/Context.h

@@ -117,7 +117,6 @@ public:
 
   Timer                               timer_init;
   Timer                               timer_load;
-  Timer                               timer_sync;
   Timer                               timer_gc;
   Timer                               timer_filter;
   Timer                               timer_commit;