Anyone else experiencing this? Whenever I watch a new Youtube video, pretty much in 95% of cases, buffering is idiotically slow even though I have a 20Mbit line. Bu if I hit a Refresh (F5) button on the video that’s stalling, all of a sudden it buffers it crazy fast this time around.
Again, I don’t recall this happening with Windows Defender or Comodo (CIS). Haven’t paid attention to other AV’s much and neither have I tried it without Web Shield yet…
yes, I think I got this quite often, so Avast! is responsible ?
It was the same even when I’ve removed Web Shield and Mail Shield using Modify option. After removing avast! and going with Windows Defender, no more buffering issues.
I have unlimited broadband (Ultra Fast Fibre Broadband) with an download speed of 100 Mbps and upload speed of 20Mbps. I am using the latest stable version Avast Free. I have experienced this very few times and at present it doesn’t appear anymore. RejZor probably sometims ISP faces some minor technical issues. When I see youtube videos it goes but it buffers for a while and I hit refresh and it continues to go normal as usual. Maybe it was a issue with Avast and they fixed it, most of the time ISP gets the fault.
It is nice to have a old system to test with.
You will notice slowdowns a lot faster 
Yes, avast is slowing down the buffering.
The culprit is (as it has been since version 2014 of avast) the webshield on my system.
Disabling the webshield solves it for me.
Is there still that Intelligent Stream Scanning option in the Web Shield ?
I don’t believe it is there for XP in the latest avast versions, but it is for win7 and later I believe.
You could try leaving the web shield enabled and disabling the Intelligent Stream Scanning option - Web Shield Customise > Main Settings.
Disabling the Web Shield leaves you without protection so that’s not a good fix. 
Intelligent Stream Scanning is still in the cloud version on XP.
I guess it also still is in version 2016
I checked first - it isn’t on mine.
But that isn’t important, the suggestion was for others in this topic who do have later OS versions, so the option should be there for them to try.
Don’t Notice too much buffering on youtube with my newer system here, AMD FX 8310 Eight Core Processor, and 150mb internet from Comcast, I’ll have to try another video in evening later and see if I notice anything. I do notice videos stalling on older XP Sp3 Laptop though, so normally I end up watching videos on Desktop PC, or Android Phone
Webshield is at default settings on both systems
I wouldn’t consider a Core i7 5820K @ 4.5 GHz with 32GB of RAM as “weak”…
And yeah, still not a single buffer problem which were regular when using avast!.
That feature also seems to effect regular browsing.
Well my laptop is expected to stutter on youtube, it’s so old, Intel Celeron M, 1.6ghz, 1.5gb of Ram, DDR2, 120gb hard drive, XP Home SP3, so I always expect that one to stutter if I play videos on it, Desktop well doesn’t stutter too much lately
RejZor, what edition of Avast did you use - Free or AIS/Premier with the Firewall? Thanks.
Free version. Build 2253.
RejZor, the only component in Free, that has a theoretical potential to affect browsing (with WebShield removed) is AOSP browser plugin? Did you have it installed and what browser did you use? Did you reboot after WebShield removal? Thanks.
No, I don’t use the browser extension. I did make a reboot after removing Web Shield.
I don’t know what’s causing it, but even after removal of Web Shield and Mail shield it was still happening. But after I’ve entirely removed avast! and used Windows Defender, not a single case of buffer stalling on Youtube. Are you sure it’s not some other driver interfering or still being hooked or something?
RejZoR, could you please try to enable profiling in windows?
You need first “Windows Performance Toolkit” available here
https://www.microsoft.com/en-us/download/details.aspx?id=39982
And after run these commands from cmdline and try to simulate your problems.
xperf -on Latency -stackwalk profile
“Your scenario goes here…”
xperf -d mytrace.etl
more info about windows tracing: https://randomascii.wordpress.com/2013/04/20/xperf-basics-recording-a-trace-the-easy-way/
or more geeky for you here: https://blogs.msdn.microsoft.com/pigscanfly/2009/08/06/stack-walking-in-xperf/
You can upload the final *.etl file for example to ftp.avast.com
Thanks