The Galaxy Z Fold 8 traps heat near the top due to basic cooling materials, causing notable performance drops over time even as the exterior feels cooler.

Across synthetic stress tests, the iPhone Duo delivers stronger sustained gaming performance thanks to more effective thermal management, while the Galaxy Z Fold 8 throttles more under prolonged load despite a cooler overall exterior.

The iPhone Duo uses a cooling design that dumps heat away from the processor and disperses it across the body and display, supporting better sustained performance with less throttling, even though it feels warmer to the touch.

Heat is distributed more uniformly on the iPhone Duo, with exterior temperatures around 103°F and a higher sustained performance, compared to the Galaxy Z Fold 8 which shows a CPU hotspot and exterior temperatures around 96°F, corresponding to lower sustained performance.