Here is a table showing the virtual and total CPU time required by LISTSERV to run an arbitrary benchmark on several releases of CMS and machine modes. The benchmark is reasonably representative of the type of work LISTSERV may have to do; it includes a DISTRIBUTE job and a REXX intensive X-LUPD job. It does not include anything based on COPYFILE, so it will not be representative if your main application is file server functions. COPYFILE has been considerably improved with CMS 7, but is not used very often by LISTSERV. Nothing has been done about EXECIO yet. Eric +--------------------+-------+-------+-----+ | Environment | VTIME | TTIME | SIO | +--------------------+-------+-------+-----+ | CMS 8 (370 mode) | 9.81 | 10.46 | 131 | | CMS 5.6 (370 mode) | 9.20 | 10.07 | 158 | | CMS 5 | 8.76 | 9.59 | 153 | | CMS 4 | 8.76 | 9.46 | 160 | +--------------------+-------+-------+-----+ | CMS 5.6 (370 mode) | 9.20 | 10.07 | 158 | (copied for reference) | CMS 5.6 (XA mode) | 9.71 | 10.53 | 149 | +--------------------+-------+-------+-----+ | CMS 8 (370 mode) | 9.81 | 10.46 | 131 | (copied for reference) | CMS 8 (XA mode) | 10.53 | 11.18 | 131 | | CMS 8 (XC mode) | 10.40 | 11.04 | 131 | +--------------------+-------+-------+-----+ PS: Due to the nature of the server, small difference in the figures are not necessarily significant and could be due to stray 'Sent file' messages or the like. That is, the last digit may not be significant. Tens of I/O's and tenth of seconds definitely are.