What is the resolution of the composition you're rendering? What are your output settings? Are you able to post a copy of the project file for assessment?
I have it at a resolution that is best for the shadow screen we are going to use to project upon. It is 500 px By 800 px. So a 5:8 aspect ratio. Resolution is at full. 1.5MB per 8BPC frame. I don't see a spot to attach the project file for you, otherwise I would. I have been able to do other basic effects such as camera tracking and depth of field blurring and unmasking words as they are being written by a hand that is writing, but when I take the text and try the particle playground effect, it freezes the program, sometimes crashes while trying to render, and if it doesn't crash, it projects the rendering to take hours.
It has been a headache. hahaha
Sorry, file attachments have been eliminated from this forum due to abuse & security issues. You would need to post with another host and provide the link here - even via Yousendit would do?
How many particles are being created in your comp? PP is an absolute render hog, and a nightmare to use, frankly. You may wish to investigate a more modern and efficient particle option, like Trapcode Particular or Trapcode Form. Here's a tutorial on using Form to do a text-to-sand effect.
Other AE plugins that may assist in "shattering" a layer are CC Pixel Poly or Shatter.