LOOKUP is implemented at two locations: the U.S. Bureau of the Census and Lawrence Berkeley Laboratory. Both LOOKUP servers use a shared pool of CD-ROMs in the University of California CD-ROM Information System.
For a given query, differences in performance are due to system overload and the geographic locations of the LOOKUP servers and the CD-ROMs. Presently, most of the CD-ROMs are physically located in California.
To improve performance for local users, system managers are encouraged to (a) implement LOOKUP at additional locations and (b) install additional CD-ROMs for shared use. The CD-ROMs used by LOOKUP are available at modest prices from the Bureau of the Census.