Thanks Bob! This becomes interesting....
I only experimented with the Application Manager, not the config map browser. Your two initial suggestions for the Application Manager didn't help - but turning off Enhanced List Widgets altogether completely solves the problem.
Without that option change, I thought I may be seeing the slowness only in an Application Manager that had been brought up in an image and the image saved. That is, that I wouldn't see it when bringing up a new Application Manager in an image. But then I have seen that too.
Another finding - despite what I wrote earlier, I have also seen the slowness in a VA 8.0.0 image's Application Manager.
Note that Matt and I have Windows 7 laptops. In the same office, another colleague of ours on XP was not seeing the problem. Suspecting a network problem, I plugged my laptop into the latter Ethernet connection - and still saw my usual slowness. So it sure seems like this slowness is specific to Windows 7.
Another colleague suggested I try "Windows XP Mode" on my Windows 7 laptop. And inside this VM kind of thing - I don't reproduce the Application Manager slowness. So perhaps that proves the problem is not with my machine's hardware etc. but with Windows 7…