I don't know if this site runs with multiple "threads" or "processes", but if it does, such things tend to only show their vulnerable spots when heavily stressed with volume or simultaneous exceptions. If two different processes try to use or modify the same data at the same time, the potential for "funny behavior" increases, and entirely different kinds of software are needed to mediate the potential conflicts.
Maybe (MAYBE) an increase in forum activity plus the extra load of the NGA sections of the site has caused things that used to work flawlessly or almost so, now glitch often enough that heavy users notice it.
This is a pure guess.
Maybe (MAYBE) this is one of the reasons for Dave re-working the code behind the site. Dave and Trish and Jon have never said that; I'm just speculating. Integrating NGA, totally re-designing the site,
and making it very customize-able would be more than sufficient reasons all by themselves!
The thread "Changes are coming!" in
Site Talk forum
P.S. The rollout was originally planned for this month, and it would be just like Dave to MEET such an ambitious deadline, unlike so many "big, professional software companies".
But since I'm guessing and speculating wildly, I'll make one more guess. If Dave has to choose between "fast" and "even better", he'll go with making ATP / NGA / Garden.org EVEN BETTER. Even if it takes a few more days, or even weeks. Even if testing the changes is slow, and polishing the chrome takes time.
"Good" software is really hard to write.
"Great" software is even harder, takes longer, and few people can create it at all.
"Bullet-proof" multi-threaded software is somewhere between "much harder" and "almost-impossible".
It's hard to write and slow to design and implement.
Big software projects are MUCH harder than small or medium-sized projects, and take MUCH longer for normal designers.
Since the site is going to be "great", "bullet-proof" AND bigger, meeting the original deadline would be astonishing even for a big, highly-paid team working 12 hours per day. I hope Dave isn't losing sleep!