To reduce the memory use, the old threads have only a flag to signal if they have comments or not. The comments are not loaded and the system doesn't know the comment count.
For the recent threads and when someone open an old thread, the comments are loaded and now the system can display the comments count.
I'm guessing:
To reduce the memory use, the old threads have only a flag to signal if they have comments or not. The comments are not loaded and the system doesn't know the comment count.
For the recent threads and when someone open an old thread, the comments are loaded and now the system can display the comments count.