Let me know if you have any questions or would like to chat about doing an internal upgrade. However, I’m guessing this isn’t something you’d want to tackle (I wouldn’t recommend it unless you’re very comfortable with the idea of doing it), but if you are I’m more than happy to chat to you about it. I upgraded the same model before Christmas so that it had an internal SSD for storage and a lot more RAM.

While this iMac is not officially upgradable after purchase, it can actually be done.

To install macOS you will need to reformat the drive so that it’s formatted as a OS X Extended (Journaled) drive and that its 'scheme' is GUID Partition Map.

If you opt for a 500GB external SSD instead of a 1TB one, you may want to consider having your Photos and/or iTunes libraries stored on your internal hard drive instead.

Once set up and running okay, you can use the internal hard drive as storage.

The main thing is that you have enough space for your macOS installation and all your apps.

You don’t necessarily need to buy a 1TB model (although this would be ideal).

Once you have the drive you want, you will need to install macOS onto it and migrate your data. Some examples of the types of external drives I mean are: And remember, it needs to connect to one of the two Thunderbolt ports (not one of the USB ports). Do not get confused by USB 3 - this is not the same as USB 3.1. However, you’ll probably find Thunderbolt models are too expensive, so opt for USB-C / USB 3.1. USB 3.1) as its interfaceīoth of the above are critical if you’re wanting to improve speed.

it supports either Thunderbolt or USB-C (i.e.

it’s definitely an external SSD (and not just a hard drive).

Since your iMac has two Thunderbolt 3 (USB-C) ports that support speeds up to 40 Gbps (via Thunderbolt) and 10 Gbps (via USB 3.1 Gen 2), the easiest solution is to use an external SSD that’s connected via one of these ports and to install macOS on that and use that drive as your main boot volume. To fix this you really need to address this bottleneck. Your mid-2010 iMac would have had a 7200rpm Hard Drive. Your iMac has a 1TB 5400rpm SATA Hard Drive and this is what’s causing the bottleneck.

Mac mini mid 2010 very slow