"Saving to OF cache" problem

While editing or creating a new task, the “saving to OF cache” window will always appear causing a 2 to 3 second delay. Is this because of my hardware specs ? or something else ? any suggestions would be great !

Hardware specs:
2007 imac
4gb of ram
2.4 dual core

While your hardware is one part of the overall picture, it might also be that your OmniFocus database is growing and contributing the the reduced performance. You could try the steps in support article on reducing database size to see if that gets OmniFocus performing more optimally again.