couchbase optimization and performance tweaking

Hello,

I am testing out couchbase as a potential drop in replacement for memcached. I am using 4 apache/php frontend boxes running RHEL5 that are connecting to a moxi-server on their respective localhost. The moxi's then connect to 4 non-replicated couchbase servers in cluster (totaling 80GB memory, ~60% full with a pre-load). Although I will eventually want to leverage replicas, my current goal is to achieve as good or better performance than our current memcached setup before exploring added features.

I am still running default settings so far during preliminary testing (just setup today for baseline comparisons) and am noticing a degraded performance of around ~30ms with my couchebase setup vs legacy memcached using a simple hash in php. Normally, the ease of use, fault tolerance, and management tools would be enough, but I cannot afford to give up any response time. I was hoping that someone could point me in the right direction for key variables for performance tuning? I have read through both manuals for couchbase 1.8 and moxi-server and am contemplating increasing the thread count for moxi-server, but am worried about the impact this may have on my apache instance. Neither webserver nor couchbase server are really seeing much load (sub 1) and their memory consumption looks fine. Is there an easy indicator in the proxy stats on moxi-server to tell whether or not the bottleneck is the number of available connections?

Thanks