Slow operations

Boot into Recovery (Command R) and from the dropdown menu: Utilities>  Disk Utility> run the First Aid on your Macintosh HD. If errors are found and repaired, run again until no errors reported.


High Sierra Recovery http://support.apple.com/kb/HT4718

To trouble shoot further you can:

Try a SafeBoot https://support.apple.com/en-us/HT201262

Takes noticeable longer to get to the login screen, does a 5-15 minute disk repair before it fully boots up, and certain system caches get cleared and rebuilt, including dynamic loader cache, etc.

This test will tell you if third party interference; extensions etc are not loaded in safe boot mode.

Test issue in another user (or guest user) account  https://support.apple.com/en-us/HT204443

This will tell you if it a universal issue or isolated to your user/admin account. 

˜What all 3rd party extensions are you running? 

EtreCheck is a simple little app to display the important details of your system configuration and allow you to copy that information to the Clipboard. It is meant to be used with Apple Support Communities to help people help you with your Mac.

http://www.etresoft.com/etrecheck

Use the Note tool on the bottom of this editor's toolbar, as shown in the image, to copy and paste the output from EtreCheck.