One issue that seems to pop up often is that the syncing capability in Google Apps Sync can sometimes be slow and cumbersome. That's usually related to the amount of mail that you are actually syncing. For example, if you have this threshold set to unlimited then the application will be working to keep track of everything on the server which over time could slow down the sync tremendously.
Fortunately, you can easily change this setting by right clicking on the Google Apps Sync icon that is located in your lower right hand corner taskbar.
You'll then have to option to modify the size to 1GB, 2GB, 4GB or unlimited.
There is one thing to note about changing these sizes. Once your local mail file has exceeded one of these sizes, you will not be able to revert back because the file itself has already exceeded that limit. When that happens, your settings menu may look grayed out like this.
One thing that you could try to do to fix this problem is compact your Outlook local mail file, also known as a PST file. You can read more about how to do that here.
Do you use Google Apps Sync for Microsoft Outlook? Have you changed the local mail file size limit?
You'll then have to option to modify the size to 1GB, 2GB, 4GB or unlimited.
There is one thing to note about changing these sizes. Once your local mail file has exceeded one of these sizes, you will not be able to revert back because the file itself has already exceeded that limit. When that happens, your settings menu may look grayed out like this.
One thing that you could try to do to fix this problem is compact your Outlook local mail file, also known as a PST file. You can read more about how to do that here.
Do you use Google Apps Sync for Microsoft Outlook? Have you changed the local mail file size limit?