Spinning beachball in Pages

Hello !

More and more often I'm getting the spinning beach ball while I'm using pages. Once it starts it goes on indefinitely and I can only stop it by restarting the computer. Very frustrating while trying to work! Having read an article about this I've checked the activity monitor and the only app showing any usage (apart from activity monitor itself) is Pages at 1.4%. I don't believe this happens with any other app.

Any suggestions ?

My MBA is only a few months old ( 2013 ) and I save most things to an external drive so I don't imagne it's a storage problem. I don't use games films, or anything else that would slow things down.

Thanks in advance !