ExtJS 4.2 - Possible causes of a “Sychronous XMLHttpRequest” warning?

Question

Good day, sorry for the seemingly broad question title.

I am building an ExtJS4 application using php and sql for the user data. Everything was going fine until one

Answer 1

Not sure about the main question, never seen that before with extjs 4 apps I have written.

For the question in loading the application faster you should be using sencha CMD to produce a concatenated and minified version of your source for using in a production environment.

Edit

I just came across this SO - "Synchronous XMLHttpRequest on the main thread is deprecated" using nodejs app.get or http-server

Talks about the same issue but with a different framework and comments suggests its an error on client side. Have you changed much lately with how your are fetching data from the server?