130,000: RAW and PSD files mostly. All image files, catalog and preview files are on a FW800 drive. A maxed out iMac, but without a SSD drive, is the host. The performance is pretty bad when working from the bulky master catalog, so I tend to work from much smaller assignment-based catalogs, and then import final work, once it's complete, into the big master catalog. I gather from reading here that the biggest improvement I might find would be in placing the catalog file on the boot drive, and making the boot drive a SSD - but I've not tried this.