This paper presents an evaluation of the performance of a consistent checkpointing mechanism that has been integrated into a modular Mach microkernel based operating system. We have measured the performance overhead of checkpointing for several workstation-typical applications: number crunching and office tools. This has been done using specific servers which were added to a standard Mach 3.0/BSD system. Measurements are performed for failure-free executions by varying the number of checkpoints and thus the amount of computation lost in the event of a crash. Our initial results showed a time overhead of about 3% for up to 20% work lost in the event of a crash. while we get an overhead between 16% and 23% for up to 1% computation lost. Also, when porting interactive office tools such as the micro-emacs text editor, we get a maximal checkpoint duration of 1.4 second on our prototype machine that is as powerful as a Sun 3/60. Based on these results, we argue that checkpointing can be integrated into a modular micro-kernel based operating system without degradation of the system performances.