Upload & Sell: Off
For Win7 and Vista (people still use this?)
Hit Start, type "%appdata%" (no quotes) and press enter.
Open 'Adobe' folder
Open 'Lightroom' folder
Open 'Preferences' folder
Rename "Lightroom 4 Preferences.agprefs" to something else (like "old lightroom 4 preferences.agprefs").
Start Lightroom (and make sure you choose your correct catalog). This probably killed a few of your settings, so you can redo those if you feel this sped things up. If you don't feel it's any faster, just repeat the steps above, deleting the new preferences file that Lightroom created and renaming the old one back.
Geez! Why didn't I do this sooner. That made a world of difference. This is the fastest LR has EVER been for me. It still delays the initial develop module startup; but dear God, it's blazing fast the rest of the time now. Preview/Grid loads are finally instant! It's so fast now, I may never do another update. lol Thanks for the easy instructions Alan.