Adriano, there are 2 known issues to be enhanced re/performance in metacache - first of all, indices on IDs in system tables are needed in order to make load into cache faster. Next, hash on names of objects should be very useful. But first of all stability issues to be finished.
BTW, comparing on DEV_BUILD is a kind of nonsense - with a lot of added asserts (that do not affect release build) debug one definitely becomes slower.