I just did some more testing and now have a clue as to what is happening. I has to do with the complexity of other objects in the model.
When I started the testing, I just entered a bunch of 2D text instances. As the number of entries increased, I saw some very minor slow down so I then went and added my normal car wash equipment to the model. With the addition of each piece, particularly more and more complex ones (equipment with many component instances) adding additional text object began to slow down. It started taking even longer to edit existing 2D text instances.
So, it looks like the more complex the model becomes, the longer it takes to both add and edit 2D text instances. It also seems like editing existing instances takes longer than adding additional ones.
Maybe TIG will be able to address this in some way. As I said in my earlier post, I had reached a point where it can take 4 to 7 minutes to edit a 2D text object.