/proc/sys/vm/overcommit_memory

Кто-нибудь пробовал? Помогает?

7.3.3 Sluggish old low memory machines

For some old low memory systems, it may still be useful to enable over-commit of memory through the proc filesystem:

     # echo 1 > /proc/sys/vm/overcommit_memory


http://www.us.debian.org/doc/manuals/reference/ch-kernel.en.html