Lightroom :: Unusable Import In LR4 And LR3 From Card Reader

Just upgraded my primary catalog to LR4. The LR3 import problem that started in ~3.3 or 3.4 has not gone away. Import effectively hangs the app.
 
I have a 6 proc AMD 1055T, Win7x64, w/ 16GB ram, an ATI 5770HD video card driving two monis, one 27" and one 24", and a ton of disk space (4 hd: c 384 free of 931, x: 191 f of 1.36TB, y: 1.55TB f of 2.72TB, z: 1.4TB f of 2.72TB). Free space isn't the issue. I usually do have several network shares connected; disconnecting them and removing all optical media makes no difference. My primary catalog has ~30,000 images When I try to import, the dialog itself takes up to a minute to open.

Eventually, the select source prompt appears; clicking on my usb2 card reader causes the dialog to disappear for a long time, sometimes > 2 minutes. The busy icon is displayed.If I'm super patient, the import disalog will open, but can take many minutes (3-5) to display, and once displayed, the busy icon remains and the dialog is not interactive for another long period, for example, right now, it's been > 10 mins on the 8GB card I'm trying to import from, import dialog visibility comes and goes, interacting with the scroll bar works, but so far I've only been able to scroll about half way thru the picture previews
 
This is obviously unusable. I've perverted my workflow at this point to be:

Copy images to temp folder in pictures hierarchy Sync temp folder, adding new images, without showing the import dialog Then, in Library view, I copy the new pictures to their final dest in my pictures folder hierarchy.
 
I just converted the catalog, so presumably it's optimized (optimizing made no difference in lr3.6 perf). As I said, this perf problem started in 3.3 or 3.4. ABout the only improvement I see is that I was able to successfully cancel the import; in 3.6 the app just stayed hung.