Feature request from fr0x, posted on GitHub Feb 23, 2015
This may be fixed in Magento 2 (I dont have a current 2.x install to check but recently ran into this in a 1.6.2 install).
The Manage Label / Options screen when you are editing an attribute has no limit on the number of options it displays. For one attribute, we have thousands of options. The admin screen tries to load every single one and it tends to cause the browser to crash/hang.