Single-ISA heterogeneous multi-core processors have been demonstrated to improve the performance and efficiency of general-purpose workloads. However, these designs leave some performance on the table due to the common assumption that the cost of migrating a program from one core to another is high. This high cost is due to the reliance on the operating system for a migration via a context switch. Many programs exhibit very fine-grained changes in behavior. A high-cost thread migration requires infrequent migrations, as the migration penalty must be amortized. In this paper, we investigate the impact that thread migrations impose on single-ISA heterogeneous systems.