Recently Branchable was having a problem, most often in the early morning (US Eastern), where pages would take a very long time to load. We've diagnosed this, and put in a fix.
What was going on was that when certian very large ikiwiki sites would be rebuilt, this blocked attempts to modify them. Behind the scenes, ikiwiki processes piled up waiting on the build to finish. While Branchable handles such load without difficulty, Apache has a limit to the number of clients it can serve at a time, and this would sometimes reach the limit. When it did, all web page accesses would slow to a crawl.
We've fixed this problem at multiple levels. Our web server now has a much higher limit to the number of clients. At the ikiwiki level, it's been modified so it can detect this situation, and, rather than waiting around, display a "Please wait" page that periodically refreshes.
The "Please wait" page is currently only enabled for a few sites that were causing the problem, as we test this new feature, but we anticipate enabling it by default. Since the user was waiting anyway, and this page can display a nice image, I feel it's overall a user interface improvement. That said, I continue to hope that one day ikiwiki will be modified to not block other site modifications while a long rebuild is going on.