I wouldn't reset the extradata when you pick something up. Only when you clear your inventory it would be nice if the extradata out of wired_items would be deleted.I prefer having independent records, besides that is more work than improving the current system. You'd have to check for LTDs and so on.
I'll look into speeding up the purchasing, but again - configure your MySQL properly and you'll see a difference.
Go on Habboon and purchase 100 items.
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Also, as mentioned above each furni may have different extradata - which shouldn't be reset on pickup, trophies etc.