Comment 10 for bug 1593456

Release Note

Several performance tweaks were made so that Horizon would render certain pages faster. First, more network-related API calls are memoized within one request, so that they are no longer duplicated in case both Quotas Usages and Networks panel both request them in the same request. Second, Quota Usages was extensively rewritten to make API calls to Nova, Cinder and Neutron in parallel, so that Quota Usage calls complete several times faster. The same parallelization technique was employed for Instances and Networks pages, where requests to Neutron were made, since they were the main contributor to Horizon's performance degradation. Third, memoize decorator was fixed to work with parallelized calls and do not start a duplicate call in case there is one already in progress (by means of threading locks).