This blog was acting sluggish. My webhost said something was eating up compute cycles because of large numbers of database hits. I deactivated plugins one by one and looked at the results after a couple of days but there was no difference. I installed a CDN via the excellent W3TC cache plugin and while the CDN is great, it didn’t solve the problem.
I then deactivated Jetpack, the one plugin that I hadn’t deactivated before because it was from wordpress.com and I assumed it couldn’t be the problem.
Jetpack was the problem. It apparently is a total resource hog. Once I deactivated it, the blog immediately became much more responsive. The stats now clearly show the difference.
More on Jetpack bloat.
There is an unofficial JetPack fork, Jetpack Lite, that only contains Stats and wp.me.