mac suddenly slowed down

You are thinking linearly which is logical, however mechanics don't always follow a linear ( meaning logical) pattern. They sometimes work fine and a moment later act flakey and then return to normal. When you get HD errors, believe them, HD's don't magically repair themselves.

The reason your iMac is slow is due to the 5400-rpm hard drive. It also appears to be failing. While this hard drive found in your Mac is perfectly suited to light tasks, such as email, web browsing, etc., for more advanced tasks, and for users who want the maximum performance from their Mac, this hard drive does have its limitations. Luckily, you can use an external SSD as your startup disk to run macOS and all your data from that. It will make your Mac 10 to 30 times faster for storage, and in turn, make your entire Mac system much faster. For more info, instructions, and what external SSD to buy, please see: How to Setup and Use an External SSD as your Startup Disk on a Desktop Mac - Apple Community.

Another option is to replace this Mac with a new Apple Silicon Mac: Mac - Apple.

Thanks for the report, the hard drive is failing and needs to be replaced. What I (and many others) recommend is to buy an external SSD, then clone the internal HD using either SuperDuper! or Carbon Copy Cloner to the new external SSD and then make the SSD your boot drive. On a 2017 I would recommend one of the 2 solutions:

1. OWC Mercury On The Go Pro & a OWC On the Pro Go Power Adapter or
2. https://eshop.macsales.com/item/OWC/S3D7P6G960/ and a https://www.amazon.com/Drive-Adapter-Cable-Support-Black/dp/B07S9CKV7X/ref=sr_1_4?crid=DN8W85LTSQ7L&keywords=SATA+SSD+adapter+cable&qid=1658001607&sprefix=sata+ssd+adapter+cable%2Caps%2C139&sr=8-4

All that copied was a filename,. Try this:

1) Make sure Etrecheck is open and showing the report you created

2) Find "Report" in Etrecheck's left-hand contents pane:

3) From Etrecheck's "Share menu icon, select "Copy report":

⚠️ NOTE: Please do NOT highlight the text in the report before copying. That will scramble the formatting and may let personal information slip through Eterchecks' privacy protection.

4) In a reply in these forums, selected the :Additional Text" icon:

5) Paste into the the resulting box:

You seem to have steps 4 and 5 working. It appears something went walkabout when trying to copy the report.

Some iMac models have user-replaceable parts, such as hard drives. Best to contact Apple Support directly to know if your iMac's hard drive can be replaced without buying an entire computer (or board, that in some cases costs almost the same as new computer).

That depends on the model year of the computer, if it is older than a 2017 then yes I would suggest replacing it as it will be classified (if it hasn't been already) obsolete. If it is a 2017 or newer, buy an external SSD, clone the internal HD to the SSD and use the SSD as your startup drive.

However if you post the EtreCheck report we can give you more specific advice.

Hi billfromcalgary,

Could you please upload your EtreCheck report? If you need help, see these steps:

How to use the Add Text Feature When Post… - Apple Community.

Jack

No report was attached, please try again.

Edited.