Configuring Database Caching of User Profiles
  RADIUS offers database support for caching user profiles to increase the speed and efficiency of user lookups. It is recommends to cache user profiles when the users  file contains more than 500 users.

  The builddbm  utility included with RADIUS for UNIX converts the users  text file to the UNIX DBM format, which increases the speed of user lookups.
  To run builddbm , use the following commands:

   cd /etc/raddb
  RADIUS uses the new database when it receives its next authentication request.
  To run the radiusd  daemon after the users file is converted to DBM, run radiusd  with the -b  option:

   /etc/radiusd -b
  The builddbm  utility generates users.dir  and users.pag  files that are used by the radiusd  daemon. On some versions of UNIX a single users.db  file is created instead. If duplicate users  file profiles are present, builddbm  prints the number of profiles and identifies the line number of the duplicate profiles.
  After the users  file has been converted to the .dbm  format, you must run builddbm  again if you make any changes to the user profiles.

Configure  Radiusd to use PAM modules to authenticate users by more efficient security systems.

Example of using /etc/pwd.db or /etc/spwd.db  on FreeBSD instead of  the  f lat /etc/passwd .