The presence of fault(s) in any web services-based system threatens its performability and dependability at large. To ensure dependability in the presence of faults or failure, service-oriented systems are implemented on scalable fault-tolerant architectures. However, the performability of these service systems under the influence of fault is vital for assessment to determine the behavioural impact on service provision and delivery. In this study, the performability of a fault-tolerant architecture implemented on software agent’s capabilities has been assessed via a compile-time fault injection technique under a replica-fault load in terms of service time efficiency, response stability, and computational effort. The assessment and findings empirically established that the impact of software fault injection is no degradation to the performability of the architecture solution. That is, the architecture performability under a fault load is significantly time-efficient in service delivery with guaranteed response stability at a reduced computational overhead (high throughput) compared to without fault injection. The recognition of the evaluation, results, analysis, and emphasis will serve as a veritable tool in increasing the opportunity of building web services solutions on a fault-tolerant architecture with appreciable performability for service-oriented communities.