Closing as won't fix. The problem is you size the text object really big. In the WebGL renderer every time the text object changes, it has to upload a new texture to the GPU with the new text. The texture is the size of the object, and the bigger the texture, the slower this is. Your text object is huge (827x462) despite only needing to display a small bit of text in the top left; resize it smaller and it performs far faster and can get nearly 60 FPS here on a Nexus 5.
There is not much we can do about this since this is the only way text can be rendered in WebGL mode other than using sprite font. If performance is critical then this is a reason to use sprite fonts instead.