This article tests whether there is an optimal level of research and development (R&D) intensity at which point a firm is able to maximize its performance. An advanced panel threshold regression model is employed to investigate the panel threshold effect of R&D intensity on firm performance among publicly traded Taiwan information technology and electronic firms. The results confirm that a single-threshold effect does exist and show an inverted-U correlation between R&D intensity and firm performance. This article demonstrates that it is possible to identify the definitive level beyond which a further increase in R&D expenditure does not yield proportional rewards. Some important policy implications emerge from the findings.