High memory usage on MacBook PRO retina 16Gb i7 2,5ghz
That's perfectly normal for Yosemite - the new rule is "empty RAM is wasted RAM."

The system will fill the RAM so that any process needing to quickly use it has it already available, rather than having to request more.

As you see from your pictures, the Swap file is zero, so nothing is being traded off to the hard drive. That's about as good as it gets - everything that needs RAM has all it needs &amp; nothing has to use the slow swapfile instead of real RAM.
You also have zero memory compression, so there is no pressure at all on the machine's resources. Everything is as it should be.

Old-style memory flushers are actually less than useful under the new memory handling routines &amp; will slow the machine down rather than speed it up.