Need advice on software for 2015 iMac

[Speckylicious]

I have a late 2015 iMac desktop, with retina 4K, 21.5 inch. I’m currently running High Sierra. I'm leary of downloading the latest OS, as I don't know if my computer is too old to run it. What's the best updated OS for my computer? TIA

 

[redheeler]

Mojave shouldn't perform any worse than High Sierra on a Late 2015.

 

[Speckylicious]

I have a late 2015 iMac desktop, with retina 4K, 21.5 inch. I’m currently running High Sierra. I'm leary of downloading the latest OS, as I don't know if my computer is too old to run it. What's the best updated OS for my computer? TIA

Thanks!

 

[DeltaMac]

Are you running the stock, 1TB hard drive?
Then updating to Mojave will continue to be draggy slow - and your best update would be to swap out that spinning hard drive for an SSD.

 

[Fishrrman]

If you don't want to open the iMac to install an SSD (which can be a risky job), you can buy a USB3 SSD (cheap), plug it in and set it up to be the boot drive.

Easy to do and runs quite fast.