After Effects UI lag

Also, I noticed that the crackling sound occurs when I hit preview in AE and open another application to watch or listen something there simultaneously (ie Youtube or Spotify). But when I stop the preview in AE the crackling disappears.

No, its the same.

Premiere doesn't have that problem, but don't know about Audition since I do not use that. I'm using Cubase for audio work. Everything works well there too.

Hmm. Do you get the same audio crackling from Premiere or Audition (which share a good deal of audio HW support functionality)?

Is the Scarlett set to the same HW settings as you have picked in AE?

I have a Clarett interface and had a bunch of trouble once when I inadvertantly had it set to 44.1khz (In the Focusrite Control app) where I had AE set to 48khz.

It seems that the freezing issue has been resolved. Hasn't come back yet.
But the cracking sound whilst previewing is still there. I'm using Focusrite Scarlett 2i2 with its latest drivers.

Audio Hardware settings:

Audio Output Mapping settings:

And the cracking sound only occurs in After Effects during preview. 

Yes exactly, bluetooth dongles. And whats interesting is that the my Office system uses the same monitors and the keyboard and mouse are connected exactly the same way through USB ports on one of the monitors. 

This is great news. We were really struggling here to come up with any idea as to why this might be happening (particularly with one system and not the other).

I have no idea why the USB configuration would be interfering with AE (and only AE) in this context, but that gives us a scenario we can try to reproduce here. These are Bluetooth devices with the little USB receiver dongles, correct?

I think I've found the culprit.
I was working in AE, moving a simple shape layer on the preview pane as usual, the spoken freeze occurred again but this time permanently. The mouse froze and didn't "wake up" anymore. It feeled just like After Effects had crashed and the apps window will go grey soon and show "Not Responding" or something. I waited for a bit, but that didn't happen.. I hit Alt+TAB and the command functioned properly, changed the windows and all, but the mouse was still fozen. Then I disconnected the mouses USB receiver and reconnected it to the same socket, that worked. Mouse moved around again, but froze soon after in AE.. But that seemed weird, gave me some ideas. Heres the thing - the mouse and keyboards receivers both are inserted into USB sockets in one of my monitor. And that seems to be the problem for some reason, and only in AE. I pulled them both out of the monitor and connected them straight to the computer and the laggy behaviour is gone. Put the receivers back into the monitors USB sockets and the lag is back.

I'll test and work in AE for a few days, see if the problem still exists. Let you know shortly.
Is that something you've heard before?
(And i'm sorry for my outburst here! The struggle was real.)

I'm sorry, but I've got no idea what you're talking about.

Oh and for Home Office setup I've got a USB hub connected with 7 inputs, all in use. But the hub is connected to a power outlet directly, not getting its power from the PCs USB3.0. That I don't have for my Office PC.

Whoa, this started to feel like a real investigation now. Thank you for that!

Other computers specs (Office PC):
CPU: Intel® Core™ i7-4790 Processor (8M Cache, up to 4.00 GHz)
RAM: 32 GB (4x G.Skill 8 GB, DDR3, 1600 MHz)
Graphics card: Gigabyte GeForce GTX 1080 8GB, latest NVidia Game Ready drivers
SSD hard drives, AE cache has a separate HD
OS: Windows 10 Pro

PC with the issues (Home Office PC):
CPU: AMD Ryzen 7 5700G with Radeon Graphics
RAM: 64GB (4x Kingston FURY DDR4 16GB 3200 MHz)
Graphics card: GeForce RTX 3070 Twin Edge OC LHR 8GB, latest NVidia Studio drivers
SSD hard drives, AE cache has a separate HD.
OS: Windows 11 Home

I'm doubting a bit this "system extensions or add on processes running on one system and not the other" part, because I did a format to my Home Office PC and installed the Creative Suite firsthand, and the issue remained even then with nothing else installed on the system. But here goes:
The anti-virus system is under the same license for both - Bitdefender Total Security (licensed for up to 5 PCs).
Screen capture utility is the same - Screen Recorder for Windows 11 v1.0.5.0 and a default Snipping Tool.
Webcams are also the same for both setups: Logitech C920
Keyboards the same (Logitech MX Keys), but mouses are different though - for Office PC theres Logitech G603, Home Office has Logitech G502X.
Office PC doesn't have a separate audio interface though, Home Office has a Focusrite Scarlett 2i2 with the latest drivers installed.
Both setups have 2 monitors, same brand, same models Dell P2720D which are calibrated with Datacolor SpyderX Elite.
And for the Home Office I switched to Studio drivers about a month ago with no effect.
Home Office has Steam installed on a separate SSD hard drive with a few games on it. Office PC doesn't have any of that.
Everything else is more or less the same - in addition to Adobe CS, i use also Cinema 4D and Cubase 9.5 for work, so both of those are installed on both systems. Aslo Office 2021 perpetual licenses, Visual Studio Code on both. Can't think of anything else...

Let me know if theres something I missed.