Hello Cameron,
"Loading" is about uploading the content to the GPU and preparing shaders. It can be slow and should be done in strategical moments as it may induce frame drops ( = unload/load is typically done during two pieces of a show).
"Activation" is the visibility of the element but does not imply any heavy operation. It can be used and abused of without in principle inducing any drop.
Hope this makes things a bit more clear 
Best,
Francis.
