Brand new iMac very slow, help?

Hello everyone,

I don't know if this is common but here it goes:

I got a brand new iMac two weeks ago (specs on the bottom of the post), and restored everything I had on my previous iMac from my Time Machine. It is always running slower than I expected, almost as slow as my 2007 iMac (previous one). Is anyone else experiencing this? Is this normal? Should I do a clean install and lose all the benefits of time machine backups - rendering them pointless?

Also, I know macs aren't made for videogames but having a game completely freeze my computer when the system requirements for it are about half of what I've got shouldn't be normal either, right? I end up having to do a cold restart (hold start button for 10 seconds), which can't be good for it.

Someone please tell me this isn't normal.

Please help!

Mac specs:

Retina 4K Display
1TB Storage

3.0GHz quad-core 7th-generation Intel Core i5 processor

8GB 2400MHz memory

1TB hard drive

Radeon Pro 555 with 2GB video memory