Comment 62 for bug 328232

same problem here:
after 30 min idle:

             total used free shared buffers cached
Mem: 1945 1759 186 0 92 1063
-/+ buffers/cache: 603 1342
Swap: 3816 14 3802

after echo 3 | sudo tee /proc/sys/vm/drop_caches

             total used free shared buffers cached
Mem: 1945 954 991 0 0 420
-/+ buffers/cache: 534 1411
Swap: 3816 14 3802

anyway its a big waste of memory and makes the sys inresponsible
The use of 900mb could be a reason of using 64 bit...