In some cases, if one is unckecking “intelligent stream scanning”, the page-rendering speed of websites seems to be faster. But why? Should it not be reversed?
Unlike most competitive solutions, Web Shield’s impact on browsing speed is almost negligible. This is because of a unique feature called “Intelligent Stream Scan” that lets the Web Shield module scan objects on-the-fly, without the need of caching. Stream scanning is performed in operating memory only (without the necessity to flush the contents to disk), providing maximum possible throughput.
Ah, this system I’m using is winXP Pro SP3 and in the avastUI that options doesn’t come after the Enable HTTPS Scanning. Looks like they have dropped the “intelligent stream scanning” in winXP. But it is in my win7 system.
EDIT: Back to your original question, the “intelligent stream scanning” means avast will scan the download as it is actually being downloaded (streamed) rather than wait until the download is complete before scanning the download.
So, the entire “Web Shield” works like your described “Download”, if ISS is activated:
Unlike most competitive solutions, Web Shield’s impact on browsing speed is almost negligible. This is because of a unique feature called “Intelligent Stream Scan” that lets the Web Shield module scan objects on-the-fly, without the need of caching. Stream scanning is performed in operating memory only (without the necessity to flush the contents to disk), providing maximum possible throughput.
But in some cases, ISS slows down the page-rendering speed. What determines this behavior - not enough RAM…?
Before continuing with this, let me make it clear that I’m an avast user like yourself and there are things I just don’t know (how a function works under the skin) as I’m not an avast employee. So for the most part I have a good idea of how it functions but not the underlying detail.
Yes, the Web Shield is active by default and scans your web browsing (before it is actually displayed in your browser) or in the case of downloads before they are saved to your hard drive.
It would be a very rare case when the ISS actually slows browsing (page rendering) hence the reason it is in the troubleshooting. There are many other unrelated factors that may slow browsers, so it is hard to say what is responsible.
Those with very fast internet connections (estimated at over 100Mbps) may find that the volume of data could create a bottle neck whilst the processor catches up, I don’t believe these scans are done in memory.
If you look in the C:\WINDOWS\Temp_avast_ folder this is where avast unpacks and or sends copies of a file to be scanned. What I don’t know is if the ISS streaming would be done in memory (rather than send it to the avast folder for scanning).
For speed scanning in memory would be fine assuming the system has enough RAM to support it whilst having multiple other programs running. If RAM isn’t plentiful or fast, then that could create a bottleneck (in the same way as a slow CPU on fast broadband), as other data in RAM would have to be switched out to the pagefile.sys location.
As you can see there are functions that I as an avast user can’t go into detail about, only my understand of how I see it working as an avast user.