with H.264 & H.265 H/W offloading. Its still being processed on the device, just in a different chip, that requires power and uses battery cycles. The expectation being that this is less than the CPU-equivalent.
It's not only an expectation but also the reality.
Adding all the features the T2 currently does (mass storage controller with DARE SSD encryption, audio controller for "Hey Siri", Touch ID processing, image signal processor, etc), how much in TOTAL is this reducing the load on the CPU. It's near impossible to tell, right.
It's not impossible, it's just something worthless to measure unless the goal of it is to publish a research about T2 chip or some similar study.
Anyway it is a fact that the T2 is not only reducing some of the CPU load, but also taking advantage of the low power consumption of technologies Apple designed for their ARM chips on iOS devices to add features to the Mac that previously were not possible to add, like Touch ID and always on 'Hey Siri' support, without impacting overall power consumption of their current x86 based Mac computers.
If you want to have a general idea about how much the CPU benefits of a relieve of all the former CPU load now being handled by the T2 chip, you have to look at the kind of the T2 chip tasks that were previously handled by the CPU and much of an impact those have had on battery life in previous non-T2 Mac models. Then just take that impact practically out of the equation. Of course the T2 chip needs some power to perform those tasks, but the power required by an Apple ARM chip with their own home baked application-specific integrated circuitry is virtually zero compared to that of any existing x86 Intel Core CPU handling those tasks. Just look at how iPhones with their tiny batteries have been handling some of these tasks natively ever since the introduction of iOS 7 on the iPhone 5s with it's 64 bit native encryption ready A7 SoC. If the tiny battery of old iPhones have been handling the same things the T2 chip does without draw backs on overall device battery life, how is a brand new Application specific Apple ARM chip from 2017 going to affect a Mac computer battery life negatively (with their huge batteries in comparison to an iPhone) in any possible way? The logical answer is, it does not.
For my use case, while I understand from another thread on this forum,
2017 MacBook behave during sustained CPU load, the m3 isn't significantly slower than the i7 chip but circa 15-18% difference was noted on multi-core processing which is a lot for a CPU-bound task like Xcode compiling,
It is not at all for small apps. I don't think you should worry at all about multicore performance for compiling small apps. Instead you'd better focus on single core performance, as the compiler isn't going to benefit from using several cores for compiling a small app, it doesn't matter if the computer has huge multicore performance. The compiler is simply not going to use any of that performance for compiling small apps.
The reason is that in the hypothetical case that Xcode LLVM were to try to take advantage from all the available cores for compiling a small app, the result would inevitably be way slower compilation times as the creation of multiple threads and therefore reserving their respective memory is going to take more computing resources than directly compiling the small app in a more of a sequential approach.
- wanting this device to work well enough as a standalone device for my use for a number of years would be (relatively) worthwhile the upgrade(?).
Not worth it as any bottom line Mac model is going to have software support just as many years as if it was speced out to the top. Take a look at how Apple lists what the compatible Macs for their new OS. For each Mac model just lists what's the oldest one compatible regardless of the specifications (except for the old Mac Pro models that could be upgraded after purchase so the support may differ depending of their specifications).
- Any other Macs to offload should be kept to a minimum with my workloads, else I should be buying something else!
Any Mac is a good Mac. Just buy whatever Mac you want to buy. But if you want to make an optimal use of your money when buying a Mac consider what your needs really are and buy your Mac accordingly.
But in the MacBook's favour, even using Xcode wouldn't max out the CPUs simply by being open and typing in code, but mostly during the compile times specifically and then perhaps would have heavier load while the Simulator is actually running. And yes, my apps will most likely be small.
Compiling times for small apps are not gonna be long enough to make a MacBook run slow even in the m3 case. In the specific case you where compiling a small app and then some performance hit was noticeable while using Simulator at the same time, I don't think that would last more than 10 seconds in the bottom line m3 MacBook.
In case you want a new Mac to last as long as possible, what you need to consider when choosing specifications for your device is it's scalability for your use cases for the future. So the safest choice of course would be buying the top of the line 15" MacBook Pro, but maybe not the more reasonable. For compiling small apps an m3 MacBook would perfectly fit those needs. But think about how much money you can really spend and how many years do you think your computing needs are going to be the same or not, and then upgrade your system according to that at purchase time. And the right time to make a purchase of a Mac is when you really need one because of your work needs or because the one you already have is going to be left out of any future Apple security software update.
Is there any truth in the throttled performance while on battery, on any MacBook chip? This would be another contributory factor that would sway back towards an Air... The negligible differences between the Air & MB start to compound.
Throttling on heavy workloads has been a reality some years already for virtually any notebook from the last few years, whether you are on battery power or connected to the power supply. It's going to happen also on the MacBook Air if you push it to its limits where the fan cooling is not enough. What you need to consider is if you are going to push your hardware that much and how long in your use case. For example, if the most hardware demanding task in your use case is going to be only compiling small apps, throttling is not going to be an issue, at least for the next 4-5 years or so, as we can not really predict what the hardware needs of future compiler iterations are going to actually be. And even if throttling ends up impacting the CPU performance during compiling apps, it'd only delay compiling times a few seconds–probably not more than 30 seconds in the very worst case scenario for a small app. So considering those things, I don't see any reason to go for more expensive hardware on a notebook for compiling small apps.
I'm not sure what you mean by mentioning "negligible differences" between the MacBook and the MacBook Air. The new MacBook Air is a strange hybrid quite similar to the MacBook, but actually they truly are quite different devices. The only problem I see regarding their differences is the little improvement the MacBook Air offers compared to the MacBook considering that those improvements come with draw backs in design as well as lots of matches in specifications and available prices more than one year after the introduction of the MacBook. But I don't see how ay of the differences relate at all with any throttling performance comparison between these two Macs inside of use case of compiling small apps. I think in this regard the similarities between the two models weight more than their "negligible differences". All in all, it really depends on you caring about those similarities and differences or not for your use case.
Finally, while in the MB section of the forum (apologies), but is there a baseline of how the fan operates on the 2018 Air? Aggressive coming on all the time and sustained? Or on rare occasions? And a what volume / decibel rating? Is that noticeable in everyday use?
Now, the answer to this one is one I'm curious to know too. I have a bunch of reviews of the new MacBook Air pending to read and watch, I just haven't had time to get into it. But anyway, just the fact that you are (if you really are) considering buying now the new MacBook Air or the MacBook from last year I'd ditch the small MacBook and totally recommend buying the MacBook Air. That way you'd be getting a more powerful and newer Mac for around the same money.
As of now, I can't recommend anybody buying the old MacBook. Although the MacBook was an amazing value when it came out, by now it's simply a device hard to recommend, even more when taking into account that a brand new 2018 MacBook Air model just came out rounding about the same price range. It could be said that people who bought the MacBook when it came out in 2017 made their Mac purchase of the decade, just like
@EugW did, but it's just now anymore. I could only recommend it if an ultra portable fanless machine is something mandatory for your needs right now and you can't wait any longer.
