CalTopo owner here, full disclosure that I stumbled onto this and am not a regular backcountrypost.com user.
SKLund, how have you been trying to contact me? Was there a bounce message or did you just never get a response?
On the performance front, I'd concur with the comments here that the problem is likely linked to the MapBuilder layers, and would ask if you're seeing the same issue with a different map background. I've noticed the slowdown lately as well, but my primary development laptop has been out for warranty repair for more than 2 weeks now (after Apple promised me a 3-5 day turnaround) and I decided to avoid making any non-emergency fixes while it was out, to lessen the chance of accidentally causing a bigger problem. At this point I'm getting pretty frustrated about the whole thing, and if I were to buy a new machine I could get spun back up inside of a day, but I haven't because I keep getting led to believe that my laptop will be back in another day or two.
The delayed update from OSM is because my decision to show trail mileages (which requires breaking up line segments at intersections, which OSM doesn't do) means that I haven't figured out how to take weekly diffs and instead need to do a full import followed by several days of postgis rebuilding the trail topology. So I only grab a new copy of the OSM data once every several months.
As to CalTopo's longevity, as somewhat outlined on the blog, the commercial vs hobby project train has long since left the station. My 2016 AWS bill was $50k, which isn't just operational costs but includes a lot of money spent on new development, such as the new imagery layers and offline support. Despite it being my full-time job for much of the year, profit from my schedule C was a whopping $5k.
I suppose you could look at that and conclude that I'm going broke running the site and will soon walk away in frustration. But a more accurate take would be that I've decided to make a significant investment in growing the site (which technically is owned by an LLC, which is then owned by me), because I think there's a lot of commercial potential that I'd never be able to realize without it. Fortunately I'm in a position to be able to do that, but I'm kind of past the point where I can just give up and let things collapse under their own weight. Also rest assured that if I did need an exit, there's too much commercial value in the site as-is for it to just disappear out of the blue. Someone would buy it, although maybe not at a price I'd like, or with a plan that you'd like.
That outcome is based on revenue that can be expected. 5K is not enough and I assume you put a lot of time into this. What I would do (that's me now) is just up the price of the product to make it reasonably profitable for the time you put in. Other mapping outfits should be paying a license fee for referencing your stuff.. At renew time, people can pay the price or walk. No one should be using this thing for free. If they don't want pay the cost, ciao to them and maybe Caltopo also if it is not working as a business.