iCloud Sync is Too Slow on PC or Mac? Here’s What You Can Do Instead.

by Felix Wong | 09 Apr 2022

Synchronizing numerous files with iCloud on a PC can be excruciatingly slow. When I tried to copy several gigabytes of files into iCloud, the Windows iCloud application reported: “Downloading x,xxx items” for many hours. Often, the number of items would not change.

I do not own a Mac, but Mac owners have reported similar problems. Synchronization for, say, 50 GB can take days.

I suspect the issue is due to the synchronization process. The log files show that iCloud is constantly checking for changes. If you have a lot of files in iCloud, the log files can span many gigabytes.

Regardless of the reason, there are two methods I used successfully to copy files into iCloud that worked much better than the iCloud for Windows app. These strategies are below. They assume you own either an iPhone or iPad, which sync much better with iCloud than a PC. But surely the assumption is correct, or otherwise you would not be using iCloud in the first place.

Strategy #1: Upload to icloud.com using a web browser

Uploading to icloud.com using any web browser is very fast. It is much faster than syncing files with iCloud on a PC or Mac.

There are two limitations of this method: you cannot upload folders, and there is a 10 GB limit per file.

A workaround for the first limitation is to compress a folder(s) to a ZIP tar.gz file and then upload it to iCloud. After it has finished uploading, view the file in iCloud on an iPhone or iPad using the Files app. Simply uncompress the gzip’d tarball in Files by clicking on it twice: once to uncompress to a .tar file, then to unpackage the tarball into folders and files. The iPhone or iPad will sync those folders and files to iCloud.

About the compression method

When I first wrote this article, I used ZIP to compress the folders and files. ZIP, after all, is the most popular way to compress files on a PC. But ZIP has the following pitfalls:

• Filenames cannot have special characters like single quotes or even accented letters when using Windows’ File Explorer’s Compress to ZIP file utility.
• iPads (even my iPad Pro, and surely iPhones) cannot unzip a file larger than 4-5 GB. Trying to uncompress ZIP files larger than that returns this error: “The Operation Can’t Be Completed: Couldn’t communicate with a helper application.”
• ZIP is a slower and less efficient method (i.e., results in larger archive sizes) than gzip.

Using tar/gzip instead avoids all of the above.

To compress using tar/gzip, you can use the command line on either Windows or Mac. If you are not comfortable with command lines, you can install and use the free, open-source 7-Zip program.

iPhones and iPads natively support tar/gzip. To uncompress a .tar.gz file, merely click on the file in the Files app. Then click on the resultant .tar file to unpack it.

Strategy #2: Copy the files to iCloud with your iPhone or iPad using the Files app

You can use the Files app to copy files to iCloud on an iPhone or iPad from another cloud account like OneDrive. So if you’re trying to copy files from your PC to iCloud, the sequence would be PC -> OneDrive -> iPhone/iPad -> iCloud (via Files app).

Or if you have an external USB drive that you can connect to (and is formatted for) your iPhone or iPad, you could copy files this way: PC -> external USB drive -> iPhone/iPad -> iCloud (via Files app).

Relative to iCloud synchronization on PC or Mac, this method is speedier when it works. Occasionally I got an error, probably due to network issues. Trying again often worked.

Trying to multitask on the iPhone or iPad might interrupt the process. The device going to sleep might interrupt copying too, but I am unsure. 

If you use this method and want to ensure reliability, don’t multitask or at least keep the Files app open in Split View. Also, keep the device on and plugged in.

Which strategy should you use?

Strategy #1 is better if you do not need to upload folders. If you are only uploading files, you can skip the compression and uncompression steps.

Otherwise, Strategy #2 is better if you have an iPhone or iPad free. 

In my case, I had many folders to copy from OneDrive. But I didn’t want to bog down my only computing device–the iPad Pro–with this task. Therefore, I started out using Strategy #1. I used a Windows Virtual Machine hosted on Azure that cost about 15 cents/hour for the VM, disk space, and bandwidth.

Eventually, I switched to Strategy #2. This way, I did not have to do any compressing and uncompressing.

Photo by Andrea