Thank you for that information. It helps.
I assume this is your Mac:
https://support.apple.com/kb/SP759?locale=en_US
Note, though, that it actually comes in a few different configurations. If you have the "stock" 1 TB internal drive (not a fusion drive), that drive is, unfortunately, somewhat slow, as it spins at 5400 rpm. But even if you had a fusion drive, the "hard drive" part of that setup would still spin at 5400 rpm.
CleanMyMac is actually not a good product to use. You'd be better off with the excellent freeware program Onyx, available form here:
https://www.titanium-software.fr/en/onyx.html
Given that you are using OS 10.13.3, you would need to get V3.4.2. I have been using Onyx for a long time (along with the excellent commercial disk cleanup/maintenance/repair program Tech Tool Pro), and I would not be without it. It has served me well.
The virus scan program will also slow down your machine. Macs rarely get viruses, especially if you are careful. Is there a reason why you run Intego every day? Also, how often does it run?
Also, via that link I provided for you, for Bigfish games, it is unknown whether or not it is compatible with High Sierra.
Unless you have a compelling reason, it might be beneficial to get rid of Intego. There is one excellent free program you can use, called Malwarebytes, available from here:
https://www.malwarebytes.com/mac/
Another excellent one you can use is ClamXav, available from here:
https://www.clamxav.com/sectors/home-use/
You can use ClamXAv in demo mode. Also, you do not need to run either of those every day. In fact, myself I run Malwarebytes about once a month, and ClamXAv less often.
Before you change virus programs, let us know. There is a very good program called AppCleaner (again free!) that can find most files associated with a program that you want to delete. It is available from here:
https://freemacsoft.net/appcleaner/
If you use it to get rid of Intego and CleanMyMac, it will find most additional files associated with both programs.
And it is important for you to insure compatibility of all your third party software with High Sierra. You might need to download and install updates for some of them for High Sierra compatibility.