Well, it appears that the reason my site has been really slow for a couple of days is due to a problem at 1&1. They acknowledged the issue on Twitter yesterday:
WordPress customers may be experiencing downtime on their websites at the moment. Please check here for updates:http://t.co/OV6NnVc9sM.
— 1&1 Hosting Support (@1and1help) June 11, 2014
Hopefully, they can get it resolved soon. Meanwhile, I guess I should take a break from messing with this site, and maybe go outside and get some exercise! (Too bad it’s been raining all week.)