The most critical verified improvement is in "token prefill"—the speed at which a model processes an initial prompt—which is 2.5 times faster than the previous M3 Ultra model.
These technical gains translate into concrete benefits for running "AI agents," which are programs that perform multi-step tasks rather than just answering questions.
Because the M5 Ultra increases memory bandwidth to 1.2 TB/s, local models can maintain high speeds even during long conversations with large amounts of data.
MacStories reports that this allows users to run complex research and automation workflows entirely on-device, avoiding the high subscription fees and privacy risks associated with cloud-based AI providers.
While high-end gaming hardware like the NVIDIA RTX 5090 still holds a raw speed advantage for smaller models, the Mac Studio’s unified memory allows it to run much larger models that would typically overwhelm a standard graphics card.
The M5 Ultra remains quieter and cooler than traditional PC builds during these intensive tasks.
This efficiency enables "tinkerers" and developers to use high-quality local models for coding and data organization, with a 512GB RAM version expected to follow in late October to further expand these capabilities.