I'm getting really frustrated with our late 2013 21.5" iMac. When waking from sleep, it takes about 60 seconds before becoming responsive. When restarting or turing on from being turned off, it takes 6 minutes before becoming responsive. Once it starts up, things seem to be working fine. But opening a program always seems to be a challenge. I just opened Word and it took 55 seconds to get to the start screen. Currently two apps are running: Safari and Evernote. 2.9HGz Intel i5, 8GB Ram, running 10.11.3. Using about 300 GB of 1TB SATA disk. This reminds me of the late 2000's when I was having problems with my PC. Everyone said it either needed the be defragmented, or it had a virus. That's when I switched to Mac and loved it ever since. Any ideas?