Chrome Version       : 69.0.3497.81
OS Version: 6.1 (Windows 7, Windows Server 2008 R2)
URLs (if applicable) : Any
Other browsers tested:
  Add OK or FAIL after other browsers where you have tested this issue:
     Safari:
    Firefox:
    IE/Edge:

What steps will reproduce the problem?
1. When you press the Maximize and Restore Down Browser Button (the square button) on new UI. 
2.
3.

What is the expected result?
It to work the way it used to work. The window gets smaller or bigger based on the preset sizes. 

What happens instead of that?
It lags and nothing changes. The window stays the same size until you actually use the _ Minimize button for it to refresh the size. It lags as well. The whole NEW UI has a bit of lag/slow down over the last version. 

Please provide any additional information below. Attach a screenshot if
possible.

UserAgentString: Mozilla/5.0 (Windows NT 6.1; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/69.0.3497.81 Safari/537.36