Mac Pro running slow

[Frank]

12 Core MacPro (Mid 2012): Is Running slow & Black monitor on opening sometimes

My Mac is running slow and it takes a long time to for windows to open windows. I get a lot of Black screens on opening and the monitor will cut in and out.
Ive ran Tech Tools and that hasn't helped, I was going to try the "Clean My MacX" to clear the Cashe . . . got any suggestions?

• 1-TB SSD Hard Dirve
• 48 GB memory
• OS High Sierra 10.13.6
• Video card ATI Radeon HD 5770

 

[Cory Cooper]

Hello and welcome.

-How much free space is left?
-Do you have any third-party utilities like MacKeeper on antivirus running>
-Is it overall slowness, or just in some applications?

C

 

[Frank]

Hello and welcome.

-How much free space is left?
-Do you have any third-party utilities like MacKeeper on antivirus running>
-Is it overall slowness, or just in some applications?

C

~ 875 GB Free space
~ I'm running Norton
~ Just opening folders and starting up