iMac i5 slow (very slow) 10.10.3

The fix that works in many (all?) cases for the 'discoveryd 100% CPU on Yosemite' issue, which is at least one of the issues you seem to have, is

Use 'Finder > Go' to go to this folder:

/Library/Preferences/SystemConfiguration/

Delete the file 'preferences.plist' and restart your Mac. Google for the above path if you want further details.

The Community consensus is also that you should also uninstall CleanMyMac using the developer's instructions.

Also, I've never seen EtreCheck fail to run system_profiler before. You should try using

Applications > Utilities > Disk FirstAid

to verify/repair the disk and repair permissions and then try running it again.

C.

User Launch Agents: ℹ️

[loaded] com.macpaw.CleanMyMac.helperTool.plist [Click for support]

[loaded] com.macpaw.CleanMyMac.trashSizeWatcher.plist [Click for support]

Search these Discussions for methods to remove CleanMyMac from your machine.

You have removed the King of crapware, MacKeeper, but you still have the crown prince, CleanMyMac, installed. If the developers were truthful they would call it TakeABigShitOnMyMac. As you seem to be learning (the hard way), these "cleaner" apps are scams. They are unnecessary and harmful on Macs.

You should uninstall CleanMyMac but it (and MacKeeper) may have done more harm to your OS than can be fixed by just uninstalling them. You may need to erase your HD and start over from scratch with a clean install of the OS.

I think you will want to check your disk drive with Disk Utility as pretty much the first part of your quest. If it's the original drive (I think that ST3500418ASQ probably is) five years is pretty good going. What's the 'SMART' status for the drive? Can you verify and repair it successfully also repair its permissions.

C.

You do not need to use cleaning programs. They can destroy your computer operation as they may already have done.

CleanMyMac - Uninstall

CleanMyMac2 Un-install

After un-installing, use this program to make sure you got all the pieces.

EasyFind – Spotlight Replacement

Activity Monitor - Mavericks also Yosemite

Activity Monitor in Mavericks has significant changes

Performance Guide

Why is my computer slow

Why your Mac runs slower than it should

Slow Mac After Mavericks

Things you can do to resolve slowdowns see post by Kappy

6 Easy Tips to Speed Up OS X Yosemite on Your Mac

The report didn't include how much RAM you have installed nor the model of Mac that you have? Check and report back or rerun Etrecheck and include the entire report this time.

My opinion is that if you've done the checks and your HDD ain't broke there's no compelling reason to replace it.

What I would recommend, however, that you have a plan for what you are going to do on the day you wake up your iMac and are greeted with a frozen display and an unnatural clicking sound coming from it. Obviously, at least one Time Machine backups will be part this plan.

C.

That Mac has been affected by CleanMyMac, which must be removed. Its presence may explain the apparent inability for EtreCheck to accurately extract and report certain system details. A corrupted Mac cannot be relied upon to accurately diagnose itself.

To recover from the effects of having used it, read below.

It is not reasonable to expect a Mac to operate normally after using CleanMyMac. Like many ill-conceived "cleaning" utilities, it is capable of corrupting a Mac to the point that erasing it completely is the only practicable means of recovery. CleanMyMac is not the only example; it is merely popular due to marketing strategies that are as effective as they are intrusive.

There is no practicable way to reverse the effects of having used CleanMyMac2 other than to reinstall all affected files from backups or their original sources. Its developer's uninstallation instructions are ineffective despite their recent claims to the contrary. Only MacPaw, its developer, can know the reason for that, but I can think of two possibilities: either they are purposefully leaving components behind for reasons known only to them, or they simply don't know what they're doing. Neither one of those possibilities is particularly comforting for the user.

Reinstalling OS X alone will have no effect on either removing CleanMyMac or reversing the damage it is capable of inflicting upon a system.

Follow the applicable recovery procedure below:

• If you have a backup that you created prior to using CleanMyMac, now is the time to use it. For Time Machine, boot OS X Recovery, and at the Mac OS X Utilities screen, choose Restore from Time Machine Backup. Choose a date preceding the installation of CleanMyMac.
• If you do not have a backup that predates the use of CleanMyMac, create one now. To do that read Mac Basics: Time Machine backs up your Mac.
  • The recovery procedure will require that you erase the Mac using OS X Recovery, and then create a new user whose contents will be empty. You will then be able to use Setup Assistant to migrate your essential documents including photos, music, work products and other essential files.
  • When doing so, select only your previous User account and do not select "Applications", "Computer and Network Settings" or "Other files and folders". De-select those choices.
  • Subsequent to using Setup Assistant, you will need to reinstall the essential software you may require, once again remembering to install software only from their original sources, and omitting all non-essential software.
  • "Non-essential software" is a broad category that includes but is not limited to third party "cleaning", "maintenance", and "anti-virus" products.

To erase and install Yosemite read: OS X Yosemite: Erase and reinstall OS X

To migrate your essential documents read: OS X Yosemite: Transfer your info from a computer or storage device and follow the procedure under Transfer info from a Time Machine backup or other storage device.

After cleaning out those files has this process improved?

Top Processes by CPU: ℹ️

97% discoveryd

do internet searches to prove me wrong about things,

Now you know that wives don't need a computer to do that, right? 🙂

If you have backups of the email, recipes, and other important documents, wiping the disk and reinstalling the system from the Recovery volume might be the expedient thing to do. Then you can retrieve those docs that are necessary for that machine.