You can't disable reading or writing it - the only control you have over the caching is to what extent it is used... Normal caching just caches average stuff; UBB Accelerator caching (for speeding up the board) caches more heavily.
Accelerator has to do with using compression. There is a seperate option for "Read Cached Pages" or not under Advanced. Which the description implies all cached pages. It seems if you didn't read them you wouldn't bother to write them.