Ok, I'm starting to nail things down some. Here are the "quick fix" pref changes that will make the most difference. Copy and paste... I tried linking, but the forum is eating the about:config somehow.

about:config?browser.cache.memory.capacity=8192
about:config?network.http.max-connections=2
about:config?network.http.max-connections-per-server=1
about:config?network.http.max-persistent-connections-per-server=1
about:config?network.http.pipelining.maxrequests=1 000

I still think the sysctl changes improve interactivity under load, but not enough to justify making a mess of people's systems ( yet ). Enabling swap for now should provide enough of a boost for most people.