Everytime Rapture Pro starts up it re-creates its program list: Rapture2Programs.xml.
I don't know why it has to do this every time, we used to have to use a function key to update Dimension and Rapture.
The first time you do this, it can take a very long time as it has to recurse the program folders and read a lot of files (I have 22,172 programs).
However, if you have a lot of memory, the second time it might be a lot faster as the files and directories may still be cached in memory.
But then again, a little later, if you open a lot of files, or happen to have that part of memory flushed, you will have to go through the wait again.
I use a debugging tool called TaskInfo that lets you flush the file cache, close open files, and tries to allocate all of free memory, then frees it up - thereby mimicking such a symptom.
Every time I do this I see horrific load times for Rapture Pro, but the second loads are only a few seconds long.