The growing size of software models poses significant scalability challenges. Amongst these scalability issues is the execution time of queries and transformations. Although the processing pipeline for models may involve numerous stages such as validation, transformation and code generation, many of these complex processes are (or can be) expressed by a combination of simpler and more fundamental operations. In many cases, these underlying operations are pure functions, making them amenable to parallelisation. We present parallel execution algorithms for a range of iteration-based operations in the context of the OCL-inspired Epsilon Object Language. Our experiments show a significant improvement in the performance of queries on large models.