I think the parent meant the cache tables of each node are empty (not many users yet), so the tested apps will be able to have relatively large cache tables on

I think the parent meant the cache tables of each node are empty (not many users yet), so the tested apps will be able to have relatively large cache tables on those nodes, since they aren't getting LRU'd out by other users. So the cache table for a tested app is fuller because the cache table overall is emptier.