When i open Steam client and start to play any video - it freeze every second. Process explorer shows, that Avast service use one full core of my processor during that process.
In Avast statistics i see that web-filter makes enormous checks per second of some “chunks” from Steam site (see screenshot below).
As a temporary workaround i add steam.exe in exclusions of web-filter and everything start to be ok. But i do not want to keep it there - i do not trust Steam so much.