Hi,

 

I noticed that the performance of the font size drop down in Firefox degrades if the content of the editor is sufficiently large. 

 

You can try it with these steps: 

1) Go to the page with the demo editor. 

2) Ctrl + A to select the content, Ctrl + V a few times (5 - 8 times should be sufficient to demonstrate this). 

3) Ctrl + A to select the content. 

4) Click on the Size dropdown. It should take a while before you get a response. 

 

 

Works fine in IE.