The new 2015 feature that will preview hidden components as transparent when selected in the tree is great....., unless you are working in a large assembly. The fade-in when combined with large sets of data locks the system up for several seconds. The system us unusable during the fade-in and if your "selection" was an accidental errant click, can be kind of confusing.
This should be disabled by default in large assembly mode, or configurable from the settings menus. So far I cannot find a way to disable it. Any ideas?