We have recently moved from an AS/400 model 200 CISC to an AS/400 model 600 RISC. On the model 200 we had the FSIOP, a 486/25 with 32mb of RAM, running LANServer/400 (an OS/2 variant). We now have an IPCS, a P200 with 256mb of RAM, running W/NT 4.0. On the model 200 we implemented an application using the UNIX API's (executed from RPGIV, using techniques from an article by Ted Holt) to write and read data from the IFS, using path '/qlansrv/nws/server name/disk/target directory'. The write program, processing multiple files, would run in approximately 1 minute. Now that we are on the model 600, the same write program using path '/qntc/server name/target directory' takes approximately 15 minutes. I am unable to determine if the problem lies in the implementation of the UNIX API's, in the implementation of W/NT on the IPCS, or in some other area.