Open source software have evolved into powerful tools for real-time control of mechatronic systems. They are of interest for academic purposes, as they promise high flexibility at low cost. In this paper, we investigate the performance of an open source control architecture based on the Linux Real-Time Application Interface (RTAI) through two applications, a haptic interface for surgery simulation and a setup for the micromachining of glass. Both applications demand a compact real-time system with sufficient precision (i.e. low jitter) for online process control and data acquisition. The real-time control has been realized on a laptop with a USB-port data acquisition card. Performance measurement results show that high quality real-time control can be performed up to 2kHz via USB communication, which is sufficient for a large range of robotic or mechatronic applications. Drawbacks like the need for considerable knowledge of Linux internals for successful installation as well as the current limitations are discussed and strategies are proposed to overcome these. Both setups are currently being used for ongoing research as well as for educational purposes.