Don't Buy a RTX Spark Laptop For Local AI Until You See This

Microsoft’s own benchmark shows the Surface Laptop Ultra, the flagship NVIDIA RTX Spark laptop, waiting 170 seconds before the first word on a 128K prompt. Before you spend $5,899 on a 128GB AI laptop for local AI, here’s where that number comes from and who it actually affects. Every RTX Spark vs Mac comparison argues about memory bandwidth: about 300 GB/s on the RTX Spark N1X versus 614 GB/s on a MacBook Pro M5 Max. That only describes decode, how fast the model writes back to you. Reading your prompt (prefill) is compute, and compute needs watts. The N1X runs at 45–80 W in a laptop. The sa