Sorry for the downtime this afternoon, this all happened just at the same time that Twitter went down. I suspect that my Twitter Pro plug-in was doing something odd (I tried chasing it with Firebug and YSlow! but it was so slow it was hard to get answers).
In response I disabled both the Twitter and the Blog RSS widgets on the right sidebar and installed WP Super Cache. Everything seems to be back to normal now.
Update – I added both widgets back in and they appear to render quickly. For safety’s sake I’ll leave the Twitter Pro widget off until tomorrow, the Feedburner-backed RSS Blog widget seems to be behaving just fine.
To improve your screencasting knowledge you must read The Screencasting Handbook. The author (Ian Ozsvald) also blogs.