It took quite a while but we finally worked out the details and I've received a grant to refactor the node cache.
I started working on it a week or two ago. I'm under deadline at work right now so I haven't gotten back to it but I wanted to get an announcement out.
The first part of the work will be adding some features to allow us to measure the effect of future changes. In looking at what we've already got, I found some traffic stats that vroom added earlier this year and added yesterday's most-visited nodes as a quick way to access them.
I'll follow up with more details/plans next week. And I'll make a reply that I'll keep updated with the most recent changes/status...
Thanks to all who helped to make this happen.- tye