Understanding processors

The processor generation including number of cores can make what was once a dead-slow performer much faster. So can faster storage (like sold state drives) and improved logic board architecture and bus speeds. No longer is processor speed the only factor. That is why benchmark scores are so useful as BDAqua has wisely noted.

I use the free MacTracker database for Geekbench scores but the numbers should be close. As an example, my 2017 iMac 27 5K was the hottest thing that year with its 4.2ghz quad-core i7. Today I compared it to the 2020 entry-leved iMac 27 5K and find the low-end processor tests faster:

Still, I always go for the fastest processor I can afford.

Hard to judge them, # of Cores is big factor also, RAM is a big issue for speed as well as SSDs vs. HDDs.

i3 is the baby Intel CPU, meant for longer Battery life I'm sure, i5 is the next step up for CPUs, but newer CPUs will be faster per GHZ than older CPUs.

You can get as rough idea of comparable speed from the GeekBench Reports...

https://everymac.com/systems/apple/imac/specs/imac-core-i5-2.9-21-inch-aluminum-late-2013-specs.html

https://everymac.com/systems/apple/macbook-air/specs/macbook-air-core-i3-1.1-dual-core-13-retina-display-2020-scissor-specs.html

I'd be embarrassed to sell a Computer with a 1.1GHz CPU in this bloated Age. :(

FWIW, assuming you want a laptop as you said, and budget is a consideration, you only have a choice between a 1.1Ghz or 1.2Ghz CPU in a MacBook Air. There is a very good chance a 2020 MacBook Air will outperform your 2013 iMac with most common tasks. That's assuming your iMac has not slowed due to other factors. In that case, the MBA will undoubtedly be faster.

Just to add, even the 1.1GHz i3 has Turbo Boost 2 speeds up to 3.2GHz.

Soziee wrote:

The iMac has been running so frustratingly slow, hence the ‘upgrade’ but I’m not keen if it’s going to run even worse!

This could be due to a file system issue, a software issue or a failing hard drive.

Use Disk Utility First Aid to check the file system making sure to click on "Details" and manually examine the details to see if any unfixed errors were found even if First Aid reports everything is "Ok".

To check the hard drive run DriveDx and post the report here using the "Additional Text" icon which looks like a piece of paper. If you have a Fusion Drive setup, then post the report for both the SSD & hard drive.

To check for software issues run EtreCheck and post the report here using the "Additional Text" icon which looks like a piece of paper.

If you have a failing drive, then you may be able to install macOS (or clone the existing drive) to an external USB3 or Thunderbolt 2 drive and boot from the external drive. With some types of hard drive failures booting to an external SSD won't be any better as the failing hard drive ties up the system resources due to I/O errors which macOS cannot handle.

FYI, the MBAir 2018+ has a very poor cooling system where the fan doesn't actually move air over the heatsink because they are completely separated from each other (the heatsink doesn't have a heatpipe). Plus the fan has a max speed of 8,000 RPMs compared to the max speed on other Apple laptops of about 6,500 RPMs so the fan noise will be more noticeable.

You're welcome. If you're not in a rush you may want to wait for an ARM-based Mac which by all accounts should start to arrive before the end of this year.