Size does sound like the most likely culprit.
Hold in mind that Pages does not optimize the size of photos you use. On that good side, this means that you don't have to worry about resizing things later if you make changes. On the bad side, big photos make for big documents.
You might want to invest in an app to reduce the size of those photos to something a bit more reasonable. A 5MP picture (what the new iPad camera takes) will easily print at 3 to 4 times the size of a standard 8 x 11 inch sheet of paper; with no loss of quality.
There is more to the subject than I care to cover here, but you should be able to Google some good articles on sizing your pictures for print or computer displays.
On the other hand, you should also give these common fixes a try and see if they help:
----------------------------------
When you have problems with an app it's a good idea to clear it from RAM.
Close/Clear the app: With the problem app closed, double tap on the Home button to get the multitask bar. Tap and hold on any icon in the bar until they jiggle, then tap the minus sign on the problem app. This will remove it from RAM and insure a clean start the next time you launch the app.
If that does not work try a restart,
Restart: Hold down the power button until the power off slider appears. Slide it off. When the iPad finishes shutting down, hold down the power button again until the Apple logo appears. Apple recommends you restart the iPad at least once a month.
and then a reset if that does not work.
Reset: Hold down the power and home buttons until the Apple logo appears. The iPad will reboot. This usually takes a bit longer than a restart.
