If you want to free the memory from all unused “crap” you can run this little one liner as root:
sync;echo 3 > /proc/sys/vm/drop_caches
The sync command flushes all buffers from memory to disk so you are safe that you do not loose anything. Keep also in mind that not everything from the cleared memory was crap. You dropped all caches – so expect that some things might run even slower.
