This article draws on the concept of 'performance' to argue for greater recognition of preexisting practices in the configuration of users. Through an Australian case study of a computer-based dairy decision-support system introduced via a two-day workshop to participating farmers, the article examines the assembling of imputed farmer users in the design of the software. It then explores how the designer and trainers attempt, through the decision-support system, to mobilize their network and align the imputed user with farmers' preexisting performances. The case study highlights that attempts to make workable on-farm the 'new' performances of users inscribed in the software are highly contingent on farmers' preexisting knowledge practices. These 'old' performances problematize the designer's and trainers' version of imputed users and contribute to partial translation of the decision-support system. A focus on performance is argued to provide a useful starting point in mapping the effects of preexisting knowledge practices on attempts to enroll users in technosocial programs.