I'm currently working on a motion typography project, and I did my text in Illustrator because I wanted all of the text to form a baseball diamond when it was finished. The project was 269 plain text layers.
I saved the file both as a .ai and as a .psd and opened it it photoshop to make sure it was still layered correctly.
Now when I try to import the file as a composition/composition-retain layer size, After Effects freezes and the spinning wheel pops up and just stays up. I've tried this on two different computers and I get the same result...
Why is this happening?
Give us enough information to actually make a meaningful diagnosis.
Hardware: computer, processors & cores, amount of RAM, disk drives and capacities, additional hardware like video capture cards.
Software: OS & version, Adobe applications & versions.
That's good for starters.
Is this your first rodeo?
How do you know you need that many separate layers? Is the project tha carefully storyboarded and prevized or are you just improvising?
The total size of your AI project is probably at fault.
Try opening the project in AI, save as a copy, and delete all but 25 layers. See if that comes into AE.
What the others said - more info. Aside from the computer specs, we need to know document and comp sizes, how the text is styled etc. and even things like fonts used may matter.