A recent survey suggests that many applications fail when they are deployed. If you don’t plan for performance issues in advance, during the development process, things can go pear shaped in the production environment. Performance can be significantly affected by network issues, for example: often, development takes place on a LAN, but the production environment is a WAN.
Perhaps the most telling statistic from the survey is that most IT departments (71 per cent) seem to rely on end users calling the help desks to alert them that performance problems exist. This means problems are only reported after their impact is noticed.
The survey is discussing conventional applications, but similar problems can arise with user-developed applications. If other users have different versions of the base software (spreadsheet, modelling package or whatever) Bad Things can happen. An application developed using a personal database such as Access can fail when many users try to use it at once. And, more basically, the developer often makes assumptions about file locations that are not valid for all users.