Improve performance of C user-defined routines
On UNIX™, Linux™, and MacOS operating systems you can improve the performance of C-language UDRs (C UDRs) by loading the shared libraries for the C UDRs when the database server is started. Otherwise, the C UDR shared libraries are loaded when the UDRs are first used. To preload a C UDR shared library, set the PRELOAD_DLL_FILE configuration parameter to the library path and file name. You must specify a separate PRELOAD_DLL_FILE configuration parameter for each library that you want to preload.
For more information about the PRELOAD_DLL_FILE configuration parameter, see the Informix® Administrator's Reference