iMac slow coming out of sleep mode

I recommend that you run an EtreCheck evaluation of your Mac. EtreCheck is a safe and recommended utility from a trusted developer and respected ASC contributor. The diagnostic app gathers important info about your hardware and software and reports it back to you. It is very highly regarded and meant to be used with Apple Support Communities to help others help you troubleshoot and resolve your Mac problems. The EtreCheck report will not include any personally identifiable info.

Please navigate to EtreCheck.com and download the free version. Be sure to enable full disk access when you install the app. Once you’ve run the app and created your report please post it with your reply to this message. 

You must upload the full report. To see how, please see:  How to use Add Text when posting… EtreCheck Report.

We can use the EtreCheck report to look for the things that may be causing your problem and advise how to correct them.

A big +1 on posting an EtreCheck report. Delays like you report are more likely software problems than hardware problems. Maybe you have a subscription app that has to "phone home" every time you boot the computer.

Etrecheck shows both software and hardware issues.