Hi Carlos,
If you have a read here http://www.snbforums.com/threads/asuswrt-merlin-380-57-is-now-available.29308/page-21#post-228554
and the couple of posts following it, you'll see that in Linux, unlike Windows, a high ram usage is nothing to be concerned about, Linux takes care of it dynamically as and when necessary. It's just Linux doing its job.
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