I have a bunch of .heic photos from my iphone on my Windows 11 desktop. Unfortunately, the Windows File Explorer loads the .heic thumbnails terribly slow. How can I improve this?

  • 1
    Convert your files into a non-heic format. Heic is a proprietary format that requires a plugin to load the photos and decrypt its content. There is no native integration into explorer nor the photo viewer app. To speed things up, make it a jpeg or png image.
    – LPChip
    Commented Sep 3, 2023 at 13:41
  • Try to install the HEIF Image Extensions and HEVC Video Extensions from the Microsoft Store.
    – harrymc
    Commented Sep 3, 2023 at 13:41
  • 1
    @harrymc pretty sure they need these extensions to even view the preview.
    – LPChip
    Commented Sep 3, 2023 at 13:42
  • I already installed the HEIF Image Extensions. Why do I need the HEVC Video Extensions?
    – K.Mulier
    Commented Sep 3, 2023 at 13:48
  • 1
    For HEVC Video see this answer. If you have installed both extensions, there is not much more to do, beside using a display mode in Explorer that doesn't display thumbnails.
    – harrymc
    Commented Sep 3, 2023 at 13:57

4 Answers 4


Upvoted answer is correct, but I have an even better fork.

  • Windows Explorer 11 only uses 1 CPU thread for thumbnails.
  • Old WinThumbPreloader only uses 1 CPU thread for thumbnails.

This utility solves this.

12x-50x faster HEIC/HEIF thumbnails!!!

Make sure you use the correct fork of WinThumbsPreloader that has multithreading, it is MUCH faster, at generating about 50+ HEIC/HEIF thumbnails per second by multithreading, if you have a modern 6C/12T+ CPU.


Person @arturdd forked it and fixed the turbo HEIC/HEIF generator in the @bruhov Issue Tracker, but you have to download it from the @arturdd fork.

Comment on GitHub:

Just want to add this is a really great utility - and as "it should have been"! Installed in Win11, right clicked folder structure with about 3 000 synced HEIC photos (6 GB) from Android phone and using about 400 threads (!) all thumbnails where recursively created on my laptop (8C/16T i7 10875) in just a few minutes. Really great and I no longer consider switching back to JPG for faster thumbnails in Windows at least 😊

...But use the correct fork!

There are multiple forks of the WinThumbsPreloader project (bruhov / arturdd / inthebrilliantblue), and you only want a fork that contains the successful multithreaded HEIC/HEIF support.

WinThumbsPreloader has been forked over 30 times.
The @Mfarooq360 fork is the best non-beta fork I have used, now at Version 1.1.0.


The same author of the fastest HEIC/HEIF thumbnail generator fork of WinThumbsPreloader, says Version 2.0.0 is coming soon. If you want to try a beta, Version 2.0.0 is here:


[Information current as of December 1st, 2023)

  • Thank you @Mark Rejhon! This is great! Please keep this reply updated in the coming months, so everyone landing here can see the progress of this marvellous project.
    – K.Mulier
    Commented Dec 11, 2023 at 17:46
  • Hi Mark Rejhon, I'm a bit confused. You first mention the @arturdd fork, but later on you refer to the Mfarooq360 fork. Which one do you recommend?
    – K.Mulier
    Commented Jan 13 at 15:02
  • The Mfarooq360's V2 fork is further development of the @arturdd fork, so its the latest multithreaded version in development with more settings and a nice GUI.
    – sambul35
    Commented Feb 20 at 0:17

The WinThumbsPreloader software is a great solution for this problem:


I also figured that turning off Windows File Explorer indexing can help a great deal:


Maybe slightly unrelated, but I figured out this solution to assign a default app to files without extension:

assoc .="No_Extension"
ftype "No_Extension"="C:\path\to\my editor.exe" "%1"

see How to set the default program for opening files without an extension in Windows?

  • Yes, just upvoted you. But there's a faster version, make sure you use the multithreaded fork of the original version, that can create over 50 HEIC/HEIF thumbnails per second. See the other answer! Commented Dec 3, 2023 at 6:24

I have one more solution, which approaches this in a different/simpler way, not just throwing all of your processing power at the problem, which does, admittedly, "fix" the issue (assuming you have enough cores to chug through the work).

This reddit thread suggested going to the HEIC folder's properties and on the Customization tab and change it from Optimize this folder for: Photos (the default option Windows selects when it detects photos of any kind) to Optimize this folder for: General Items. At this point, Windows stops even trying to review the HEIC files and the folder loads as fast as any other folder. You can sort, view, etc easily and quickly. Resetting this option to Photos immediately causes the massive slow down once more.

Hope this helps someone that either A) doesn't have a bunch of cores or B) doesn't care about the photos optimization (whatever that does).


Another solution besides WinThumbsPreloader. Multithreaded image thumbnail viewer: nomacs. This is the only third-party image viewer I've found that supports multi-threaded thumbnail generation.
On my 8th-generation intel 4C8T cpu , it generates about 5-6 thumbnails per second, which is about 5 times faster than the original one per second.

enter image description here

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