I guess that Avast One is still at the Beta stage or at least it feels like it. For a freshly installed application I found it heavy on memory and less than scintillating in performance. Under the skin it has a lot in common with 'traditional' Avast but the UI is obscure and there are fewer options to tune it to the user's liking. I uninstalled Avast One and did a fresh install of Avast Free 21.11. It performed beautifully and the system RAM usage reduced by 350MB. I would only transfer to Avast One under the duress of the traditional version being unavailable.
I tried these two versions of Avast on a Toshiba Satellite Pro P200 laptop with 4Gb of RAM and an Intel Core2 Duo T5550 1.83GHz processor. The traditional Avast version won by a country mile. The default settings of the traditional version are well chosen and require little modification by the ordinary user. Why Avast One? That is what I ask myself.
Avast One Essential does offer more protection than the free version of Avast.
(Firewall and VPN are included in Essential and are missing in the free version.)
Yes, the UI is different and there are fewer options when it comes to customization.
Most users never change the default options regardless of the version installed.The default options are set to offer the best mix of performance and protection. There are however still quite a few adjustments that the user can make especially one you
learn the new interface.
That's my take on Avast One which is currently installed on my main system.