iPhone 17 Pro Max and M4 Pro MacBook Pro Reach Up to 44% Higher Prefill Performance on a 27B AI Model

A user connected an iPhone 17 Pro Max to an M4 Pro MacBook Pro over USB-C and used custom software to improve prefill performance while running the Qwen3.8-27B AI model, according to Wccftech.

The reported improvement reached up to 44% compared with running the same model on the MacBook Pro alone. The Mac has 24GB of unified memory, which the report says can limit prefill speeds for the model. It does not provide further details about how the custom software uses the connected iPhone.

Wccftech also says that, even with memory raised to 20,480MB, the M4 Pro MacBook Pro is limited to a 64K context window. The report describes the model as capable when it has sufficient VRAM and system RAM, but gives no additional performance measurements or testing details in the supplied summary.