Fatal error, allowed memory size exhausted, after update to 7.x-1.5

I recently updated the entityreference module from 7.x-1.1 to 7.x-1.5. (I did this update on a test copy of my site.)

Now I am receiving out-of-memory errors on my site. It happens when I go to node/add for a content type that contains a bunch of entity references.

I am concerned because apparently this update was necessary for security reasons but I am unable to apply this update to my production site until I figure out what's causing the error and fix it.

Since I did not do each update along the way between 7.x-1.1 and 7.x-1.5, I suppose I don't really know if one of the earlier updates could have generated this same fatal error. Should I go through each update one by one, and test my site, in order to identity the specific changes that caused this error to happen for me?

Or does someone have a better idea for how I should approach this?

Thanks for any advice or clues you can offer.