Help Device encryption problem

[ArgandPlane]

I'm using a Samsung Galaxy S III 16GB and I just tried to use the full device encryption in the security menu. I set a password, charged my phone, and plugged it into power and then tapped encrypt. I accepted the prompt and then waited. It displayed a green android for about 5 minutes and then rebooted. I went into settings and went back to the device encryption options, where it was still displaying the option to encrypt the device. My question is: Considering that the process apparently only took 5 minutes instead of the hour it said, and the phone still displays the option to encrypt the device, did my phone actually encrypt?

 

[Lokvill]

I have been reading posts that people are going through the same thing if not somewhat different. I am still debating on whether to encrypt mine or not. What I want to know is if I do encrypt, will there be a performance issue (SGH-1717). Sorry I couldn't help you.