Your last remark seems to confirm what I am experiencing.
My computer (Windows 10 64bit) uses an Intel Q6600, that is a respectable quad core CPU (even though the nowadays processors are way more powerful) with 8 GB RAM.
Yet since installing this last version, avast is constantly using between 27 and 35% of the CPU resources, even when not any program is opened (beyond my utilities).
Any idea or suggestion?
It is such an enormous jump in resources usage, from avast 2015 (that ran at about 10% top), that frankly, I am beginning to think of searching a less voracious security suite!