I just installed Lightroom 4 and am trying to use the maps feature, but panning and zooming it is so slow that it is nearly unusable. I never had perf problems with LR3, and I've got a decent machine:
Windows 7 x64
4-core 2.8 Ghz CPU
8 GB RAM
NVidia GeForce GT 440
Using Google Maps on the web is as snappy as expected.
Is this a known issue? Would installing Google Earth help?