This repository just has a database dump for a Magento CE 1.9.2.2 instance that has 85k orders and 129k customers alongside the regular sample data.
Maybe eventually we can add other tools / conveniences here for load testing.
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Note that it looks like pretty much all the products are out of stock. This tends to happen when you place 85k orders :)
You will probably need to add some stock and/or change configuration settings to display products regardless of stock in order to get them to show up on the frontend.
Brough to you by MageMail - the triggered email app for Magento.