Not showing thumbnail of avi files

I have windows 10. I installed latest version of codec pack. bt when I checked to use Microsoft thumbnailer for avi files. Windows explorer doesn't show thumbnail for avi files. cleared thumbnail cache, restarted system. unchecked Microsoft thumbnailer option for avi. And thumbnails start showing

Did you disable Media Foundation or any of the Microsoft codecs? Those are used by the Microsoft thumbnailer.

Any specific reason why you want to use the Microsoft one?

I have not disabled media foundation or any ms codecs.
I have used icaros thumbnailer for all the media files, but it slows down the icon loading of files other than media(programs,etc.). so I have to install icaros but use only for those files whose icons doesn't supported by Microsoft. so I chosen to use Microsoft thumbnailer in that four options available in the codec tweak tool.

First of all, disabling Icaros for .avi does not have any effect on thumbnails for other formats.

Secondly, Icaros should not have effect on Icon loading unless you enable it for .png images. The codec pack does not use it for any image formats at all. So did you actually have that problem, or did you just read about it somewhere?

icon loading of program files (such as stored drivers files (.exe) on hdd) become slow on installing codec pack

I will talk to the developer of Icaros about this issue.

The problem of the AVI thumbnails will be fixed in next version. A fresh install of the codec pack is required, so uninstall your current version first when updating.

I have talked to the Icaros developer and he also does not know why Icons load slower for you. Explorer should not be using Icaros at all in this situation. Which icons are loading slowly? The ones on the desktop, the ones in the Start menu, or all of them?

icons of the installer(.exe) files stored in the hdd

If it only happens with installers, then maybe the delay is because Explorer is first verifying the digital signature of the files. Or it is due to the SmartScreen feature of Windows.

but I compared the speed before installing icaros and after installing icaros. and found that after installing icaros icon loading becomes slow. I never tackled with smartscreen.