This is pointless your only changing the ram amount allowed to use. In fact windows is set up to use only as much ram as needed and has a fault protection. This actually lowering the amount of ram because your only limiting windows. (it's for people running two os at the same time)
To reduce lagg you want to either get a new computer/upgrade it/edit system settings ex: Connection limits/or use a better server
Really this is no simple fix to lag it will always be a program simple things like a better ping or faster GPU can only fix that on black ops
This seams it works for you because you went on a different server...