All Intel product marketing aside, the performance of a computer is based on the slowest component, and not based on the fastest. Best performance (and price) comes from a balance of components, where one fast component can be stalled waiting for slower components to catch up.
The 8 GB and the hard disk drive (Fusion, here) are hindering your performance here.
The limit here is likely the lack of memory.
Here is why:
Why is my hard disk drive iMac so slow? - Apple Community
The least expensive option for improving performance — short of replacement — is usually an external SSD. And it probably won’t help all that much, given this looks like insufficient memory. Though maybe the Fusion is failing?
Use an external SSD as your startup disk … - Apple Community
Upgrading the internals of an iMac 21.5” iMac is an expensive and somewhat risky slog.
This thing is also seriously under-configured — or sometimes called “under-purchased” — for what is running.
It can also be somewhat possible that the hard disk is failing, and you will always want to have current backups anyway, but this looks more like Microsoft Office and Adobe Creative Cloud — neither of these app suites are lightweight — on an under-configured iMac.
To check the storage hardware, run Apple Diagnostics and DriveDx: