Large files slow the Para mode movement commands. Typing `C-c C-p t' (para-tagify) creates a tag table at the end of the Para mode file that similar to the tag table used in Info. This table lists the locations of every node. The various movment commands first look for a tag table and use the information in it if it is there. (A tag table is optional.) The tag table does not have to be up-to-date--the movement commands go to the location specified by the tag table and search in every widening circles around that location for the desired node. And if you have a node that is not yet listed in the tag table, the movement commands will still find it, but take longer.
C-c C-p t para-tagify create tag table at the end of the Para mode file
The tag table is enclosed in @ignore and @end ignore commands so that you can format the Para mode file without trouble.