Why does one dataset take more time to build a model than another?

This is usually due to the dataset size and the number of fields in it. The bigger your dataset is, the longer AI Studio will take to build the model. Nevertheless, AI Studio can build models from many thousands of instances within just a few seconds due to its distributed computing architecture. Please keep in mind that speed is also dependent on your subscription plan or specific deployment option you choose as more memory, processors and parallel Pipelines can greatly improve performance.