We have a site that was recently updated to Plone 4.3.9; before the upgrade the site was running smoothly, but after it we starting noticing huge consumption of memory when accessing the front page (a collective.cover object).
We have a site that keeps growing in memory comsumption where the total memory usage of the zope server doesn't seem to crawl to a maximum (limit to) in the munin stats but grows almost linearly over time.
One of the ideas to to figure out if there are some suspect views is installing collective.stats which can give quite detailed resource information for every call made. Maybe this can help you too.
I am not sure if this is helpful for you, but I recently learned about how to use varnish to get real user requests for hammering my plone instances.
I try to use it to warm up the zope caches, maybe it might be usable for you as a brute force approach to reliably reproduce the issue. https://info.varnish-software.com/blog/warming-varnish-cache-varnishreplay