Actually, it's a little bit of both.
The Accelerator is an option given by UBBclassic to help the board produce pages faster without the server load.* We had it running at our original server way back when - thus some links may show the "ubb/...php" links. However, it was cited by that original server as a cause of concern and shut down.
*What it does is take often used threads/links in the board and makes a seperate php version of it which is supposed to be less-server intensive than the CGI scripts. A form of "caching" that was still dynamically based.
When we moved to PowWeb, I had tried on seperate occasions to re-instate the Accelerator, but have met with nothing but problems. The last go around was causing a "time rift" between the board and our overseas members. They were seeing versions of the board that were older than we in the US were seeing.
To end these issues, I've given up on the Accelerator option. It also makes me wary of trying UBB's new PHP based Threads, instead of our CGI based Classic.