An aspect of the present invention provides for timing analysis when integrating multiple circuit blocks while balancing resource requirements and accuracy. In an embodiment, an optimized model for a circuit block is created by combining information provided by two different models of the same circuit block and performing timing analysis based on the optimized model. In an embodiment, the two models correspond to black box and interface timing models. In the optimized model, ports for which only timing arc information is deemed necessary are modeled using corresponding information from the black box model, while ports for which more accurate or detailed information is deemed necessary are modeled using corresponding information from the interface timing model. The optimized model enables the integration to be performed with a balance of resource requirements and accuracy.