Users can edit the description field in their profile. They can overload the text field (see the file below with lorem ipsum to test). It slow performance and ultimately lock their profile.

In the database, the description is a longtext type. It is possible to change the description field for a medium or a tiny one?

to replicate the issue : edit a user profil > copy the text in the txt file below > paste it in the description field of the user profile. 

I was not able to replicate the crashing page but it is incredibly slow.