1. A method in a near end network optimizer for supporting a delta compression technique for reducing network resource transmission size between the near end network optimizer and a far end network optimizer that is coupled with the near end network optimizer, wherein the near end network optimizer is also coupled with a plurality of client devices, the method comprising: receiving, from a first one of the plurality of client devices a first request for a network resource, wherein the first client device is physically separate from the near end network optimizer; responsive to determining that a version of the network resource is not stored in the near end network optimizer, transmitting a second request for the network resource to the far end network optimizer; receiving, from the far end network optimizer, a first response that includes the requested network resource; transmitting, to the first client device, a second response that includes the requested network resource; storing, in the near end network optimizer, the requested network resource as a first version of the network resource; receiving, from a second one of the plurality of client devices, a third request for the network resource, wherein the second client device is physically separate from the near end network optimizer; responsive to determining that the first version of the network resource is stored in the near end network optimizer, transmitting a fourth request for the network resource to the far end network optimizer, the fourth request including a first version identifier that identifies the first version of the network resource stored in the near end network optimizer; receiving, from the far end network optimizer, a third response that includes a differences file that specifies a set of one or more differences between the first version of the network resource stored in the near end network optimizer with a most current version of the network resource, wherein the third response does not include the entire network resource; applying the set of differences specified in the differences file to the first version of the network resource stored in the near end network optimizer to generate an updated version of the network resource; and transmitting, to the second client device, a fourth response that includes the updated version of the network resource.