1. A method for concurrent workload simulation for application performance testing, the method comprising: loading a list of recorded workloads for different tasks of a computing application under test in a workload simulator executing in memory by at least one processor of a host computer; grouping the recorded workloads by common task in a corresponding block; and, generating loads for simulating performance of the computing application under test from the grouped workloads so as to require serial execution of workloads in a common block in order of appearance in the common block, but to allow concurrent execution of workloads in different blocks.