I have difficulties enlarging fonts larger than 1296pt in photoshop!

I used to be able to make banners and font in any size.  Lately I am experiencing difficulties doing so.  I am able to enlarge fonts, but the file size becomes so large that it takes forever to process.  When I try to save the documnet in a smaller size, it never happens.  The bar goes to 14% and stopps.  Then I get a message that  I have insufficient application memory.  In the past this was not a problem.  I appreciate any help i can get to rectify this problem