When you sync items to your computer using the OneDrive app, it has to maintain a cache of the meta data of all the items, regardless of whether you have opened them or downloaded them. The meta data of changes made by other people with access to the files also need to be processed. If you have a large number of files, the overhead might be significant.
OneDrive Limits
According to Microsoft’s guidance, “Although SharePoint can store 30 million documents per library, for optimum performance we recommend syncing no more than 300,000 files across all document libraries”. 300,000 items sounds like a lot, but this can easily be exceeded if you sync an entire SharePoint library that has several years worth of data.
Selective Sync
To overcome this problem, you can selectively sync certain items from within a SharePoint library. One way is to navigate to the folder you need and sync that, but if you need several folders, it’s better to use the OneDrive settings.
Once you have synced the Library, go to OneDrive Settings
Next to the library you have synced, you’ll see an option to choose folders. Here, untick anything you don’t need to sync, and leave only the folders selected that you require. You can expand the top level folders if what you need is located a few folders deep.
Other useful OneDrive tips
If you no longer need to sync an entire library, see Stop syncing OneDrive Items you no longer need
If OneDrive has stopped syncing properly, see How to reset OneDrive
For more guidance on other OneDrive options, see Manage Storage in OneDrive
