SDK3(patch set) kv and query latency ~30% higher than SDK2 with external libcouchbase installed

Comparing SDK3 to SDK2 kv get/set latency, we see that across all latency percentiles, SDK3 is ~20-30% higher than SDK2. Here are the two tests for comparison:

SDK 2.5.0 - 24 workers:

http://perf.jenkins.couchbase.com/job/ares/17051/

SDK 3 - 24 workers:

http://perf.jenkins.couchbase.com/job/ares/17049/ 

In both tests, kv ops are against default scope/collection.

SDK3 is this patch: git+http://review.couchbase.org/couchbase-python-client@refs/changes/91/135991/3

Here is a comparison graph:

http://cbmonitor.sc.couchbase.com/reports/html/?snapshot=ares_700-3090_access_c015&label=sdk2(24workers)&snapshot=ares_700-3090_access_ae94&label=sdk3(24workers)

The only difference in these tests, other than sdk version, cur_connections to bucket and ESTABILSHED connections to master node 172.23.133.13. Perhaps these "extra" connections are causing the slow down as the "extra" connections is around 30% more than sdk2 which corresponds to the increase in latency

Workaround

Remove any externally installed libcouchbase releases from the system. When run with the built-in libcouchbase, the higher latency is not observed.