My 21.5-inch iMac, Apple's all-in-one computer, has been my faithful workhorse for nearly eight years.

But recently, I have been seeing the dreaded spinning rainbow wheel too often, even when just launching basic apps such as iTunes. In other words, my iMac is getting excruciatingly slow.

I was therefore excited when Apple announced a refresh to the iMac series in March, with the 27-inch iMac updated with the latest ninth-generation Intel Core six-core or octa-core processors for twice the performance of its predecessor.

And available for the first time in iMacs, as an optional upgrade, is the professional Radeon Pro Vega graphics processing unit (GPU).

My review unit has an Intel Core i9 3.6GHz octa-core processor, 16GB of RAM, Radeon Pro Vega 48 GPU with 8GB of video memory, and 512GB of flash storage. This configuration can be considered to be in the mid-upper tier.

Design-wise, the new 27-inch iMac remains unchanged from the 2015 and 2017 refreshes. It is still an aluminium body with a curved back that tapers to a 5mm-thick edge.

Like its predecessors, all the ports, including the headphone jack, are sited at the rear. This means you have to reach behind to insert an SD card or USB cable, which is a major inconvenience.

There is also still a rather thick black bezel around the display, which has me wondering if it is possible to hide those ports inside it.

Although I know the black colour option is reserved for the high-end iMac Pro, I would have preferred this iMac to have that option too.

Nonetheless, this iMac's Retina 5K display remains gorgeous. Its brightness level is rated at 500 nits and supports up to one billion colours as well as the P3 wide colour gamut for more vivid colours. With a super high resolution of 5,120 x 2,880 pixels, you can see more details.

I connected it to my full highdefinition monitor and found the difference in brightness and details to be obvious compared with my iMac. This was especially so when editing videos and photos.

Even for word processing, fonts looked super sharp.

Not to mention, I was able to write this review using half of the large display with the iA Writer app, while the other half ran the Google Chrome Web browser to show my latest e-mails. You do not need to get an extra display to improve your productivity with this iMac.

Performance-wise, it is among the best of its class with its latest Intel processors.

In the Geekbench 4 benchmark tests, the review unit posted scores of 6,384 (single-core) and 33,466 (multi-core). Its predecessor using the Intel Core i7 processor scored 5,687 (single-core) and 19,382 (multi-core).

In actual use, I found no discernible lags when editing 4K videos using Final Cut Pro X (FCP X). In fact, I have not experienced a Mac that starts FCP X in a mere four seconds like this review iMac.

However, its superb performance comes at a hefty price. The review unit costs a whopping $4,939, even though the price for the 27-inch iMac starts at $2,599. If you are to max out the add-in options of this 27-inch iMac model, it would cost a jaw-dropping $7,638.