Macbook

Image source: Apple.

I know what you're thinking right now: "Oh, not this rumor again." It's true, the idea of Apple (NASDAQ:AAPL) making an ARM-based Mac has persisted for years. But it's also true that actually making such a product a reality would take many years, and if Apple started the process years ago when rumors first emerged, it could continue inching closer to the end goal. Naturally, here's where you insert the risks that Intel (NASDAQ:INTC) faces if it were to lose the processor spot in Macs -- a spot it only won less than a decade ago.

One of the most prominent arguments against an ARM-based Mac has long been the performance gap between Intel chips and Apple's A-chips, but this gap is narrowing every year. In fact, the new iPhone 6s is remarkably close to the performance of Intel's low-power Core M that powers the new MacBook.

The A9 is already comparable to the Core M
Prominent Apple blogger John Gruber ran the most recent model through some performance benchmarks, and the results for Apple's latest A9 are impressive to say the least. Gruber used the popular GeekBench for his tests, and the iPhone 6s beat the MacBook in a couple of categories. That's quite an accomplishment when you consider how relatively young Apple's chip team is and a testament to how quickly the Mac maker's silicon talent is advancing to close the gap.

GeekBench

iPhone 6s

MacBook (1.3 GHz)

MacBook (1.2 GHz)

MacBook (1.1 GHz)

Single-Core

2,500

2,631

2,420

2,295

Multi-Core

4,340

5,268

5,018

4,464

Source: Daring Fireball.

It gets better. These results are for the A9 inside the iPhone 6s, while the A9X is a more powerful variant that will power the forthcoming iPad Pro. The A9X will represent the best silicon that Apple has to offer right now, and it's entirely conceivable that the A9X will top the MacBook in even more categories.

Apple's not there yet
While Apple has effectively closed the performance gap between the A9 and the Core M, Apple still has a long way to go before it can viably replace more powerful Intel chips with its A-chips. For instance, a top-of-the-line 2015 MacBook Pro with Retina display sporting a Core i7 boasts GeekBench scores in the ballpark of 3,400 (Single-Core) and 13,700 (Multi-Core). The performance gap there is still quite wide.

Under the hood, Apple would still need to recompile OS X to run on ARM-based processor architecture, which is no easy feat. That's especially true when it comes to third-party software compatibility. But Apple's last architecture transition was more seamless than anyone would have ever imagined, and it's not a stretch of the imagination to think that perhaps Apple has already started this process in secret (in case you haven't heard by now, Apple is the secretive type).

Earlier this year, Intel CEO Brian Krzanich described his company's relationship with Apple as "strong," noting that Apple is always going to go with the supplier that offers the best innovative capabilities. That may be true now, but it also ignores the very legitimate strategic rationales on why Apple would benefit immensely from transitioning Macs to A-chips in the long run.

Apple would be able to better tailor the performance and power efficiency profiles for its own needs, develop and design chips to coincide better with its own product cycles, and enjoy significant cost savings. Those cost savings would not only come in the form of chip prices, but also in terms of development since Apple could streamline its software teams under a single processor architecture.

There are some rumors that Apple could even ship an ARM-based Mac in 2016. Even though that timeline sounds unlikely, it does seem inevitable that Apple will do so one day. And that day keeps getting closer and closer.

Evan Niu, CFA owns shares of Apple. The Motley Fool owns and recommends Apple. The Motley Fool recommends Intel. Try any of our Foolish newsletter services free for 30 days. We Fools may not all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors. The Motley Fool has a disclosure policy.