Speed up iMac Performance

My recommendation for the most smooth migration is to create either a bootable clone (you can use the demo versions of SuperDuper! or Carbon Copy Cloner) or a Time Machine backup and then follow my instructions in Setup Assistant and Migration Assistant to migrate. I got that you use Carbonite but in order to make your migration smoother, you really should follow the steps in the link. Who knows what you will get with the way you are thinking about.

This method is tried and true and has worked for years and has been found to overall be the quickest, easiest and most reliable method of migrating from an older Mac to a new Mac.

Please do the following so we can get a good idea on what is going on with your system. Also, to answer your question.... NEVER EVER install any type of third party antivirus app, cleaning app or ANY other third party maintenance type apps.

Please navigate to www.Etrecheck.com and download the free version of EtreCheck. Once you have you downloaded the app and installed it, please run the report and save it. This report will help us get a good idea what has been installed on your system and help us be able to diagnose what may be wrong.

When you have your report, you can attach it when you reply to this message and we can then review it and help you determine what is needed to get your system running well again.

For instructions on how to download your EtreCheck report and attach it to your reply to this message please click https://discussions.apple.com/docs/DOC-250000211

Unfortunately, you could not use your iMac as a display.

However, +1 to rkaufmann87. I'd consider to use an external SSD and run macOS from that. It will make your Mac 10 to 30 times faster for storage. For more info, instructions, and what external SSD to buy, please read: How to Setup and Use an External SSD as y… - Apple Community.

Cheers,

Jack

Well there are a number of issues.

• First, I see the computer has not been restarted in 12 days, I would recommend restarting about 1x per week.
• The HD appears slow which may be an indication it is failing.
• The computer is a base model iMac and these machines were never designed for doing anything more than e-mail and surfing the Internet. They only had 8GB of un-upgradeable RAM and a glacially slow 5400 hard disk which is the primary bottleneck on any computer.

In short you have a 6 year old base model iMac. To get back to your question, if you want to put money into it then buy an external SSD such as a OWC Mercury On-The-Go Pro: Get Maximum Storage Within Minimum Space (macsales.com) and a 5V 2.0Amp Barrel Style AC Power Adapter for OWC Mercury On-The-Go (macsales.com) and then clone the internal HD to the SSD using either SuperDuper! or Carbon Copy Cloner and use the external SSD as your boot drive.

The next option to speed it up is to replace it, I'd consider a new M1 based Mac Mini or the 24" M1 based iMac. Either machine would be a HUGE upgrade over your current 21.5" iMac.

Your old Mac CAN NOT be used as an external monitor.

Your welcome.