This year's iPhone 14 and Watch Series 8 are not expected to offer noteworthy performance bumps over their predecessors and Apple's custom Mac processors may be to blame.

2010's Apple A4 was the first smartphone chip that the company made itself and each year, it makes a new SoC to go with its new phones. The year-on-year increase in CPU performance peaked in 2015 with the iPhone 6s' A9, and though Apple still makes the fastest smartphone chips around, yearly speed increases have slowed to the point that the Cupertino giant didn't even bother comparing the iPhone 13's chip performance with its predecessor.

Are Mac M series chips to blame for the slowdown in iPhone's A Bionic development?

The internet is rife with rumors that this year's 6.1 inches iPhone 14 and 6.7 inches iPhone 14 Max (or iPhone 14 Plus?) will be powered by last year's A15 Bionic, though Apple may change a few things here and there and stamp a new name on it.

The more expensive 6.1 inches iPhone 14 Pro and 6.7 inches iPhone 14 Pro Max are rumored to be powered by the new A16 chip, which will apparently be manufactured on the 5nm process and not the newer 4nm process on which new Android chips are based.

Even the forthcoming Watch Series 8 is expected to have the same processing chops as the outgoing model. The company is also said to be struggling with modem development, and it's not entirely clear if that's because of Qualcomm patents or hardware issues like overheating.

Are Apple's chip resources spread too thin?

In the latest edition of his Power On newsletter, Bloomberg's Mark Gurman examines whether the iPhone chip has taken a backseat because of Apple's increased focus on the M series chips that power the Mac computers as well as some newer iPad models.

The in-house Mac chips are the company's most powerful processors and have kind of upended the industry. Apple has announced five M series chips within a year and a half and is expected to launch several more over the next year.

This seemingly entailed reassigning some of the testing, development, and production resources to Mac processors. Apple's chip department seemingly demands laser precision, leading to employee burnout. Apple has also lost many engineers over the past few years.

Apple's reliance on Taiwan Semiconductor Manufacturing Company (TSMC) may have also played a part, as Apple needs the contract chip maker to produce 3nm chips in mass quantities.

All this combined with supply bottlenecks and increasing costs for chip development could be why Apple is neglecting non-Mac chips.

Gurman points out that this doesn't sound like a wise move, given that 60 percent of Apple's revenue comes from products that don't run on M series chips.

The good news is that the A15 Bionic was 62 percent faster than competing chips that powered the best Android phones, so even with minimal improvements, the A16 Bionic will presumably perform better than new Qualcomm, MediaTek, and Samsung chips.