I think this important enough to repeat this tip from the manual. I’m glad I noticed it and selectively turned off this option before my first sync.
By default, a lot of local disk space will be consumed if you don’t do this.
The desktop manual tells us:
I suspect this cannot be disabled by default by DT (more likely, it’s a Dropbox default) but maybe I’m wrong. ?
No, we cannot turn it off for you. This is Dropbox’s territory.
As suspected. Thanks for confirming.
I’m just glad I read that passage before syncing the first time. 
What can be done after the fact? I’m on a trip so I can’t check my Mac to see what setting I have. But if I didn’t disable packet sync, is it too late?
You can disable it anytime.
Thanks for this advice.
Yes, I’m sorry if I implied it would be uncorrectable. The only “bad” thing would be wasted disk space and wasted bandwidth. The disk space is reversible. The bandwidth isn’t but that’s probably only significant on a metered/tethered desktop situation.
Does this have any effect on performance, sync speed etc?
Excluding the folder should improve the performance if Dropbox.app is used concurrently.
On the desktop? I was thinking about sync performance for DTTG.
It might improve the performance too but it’s more important on the desktop.
Ok! I’m giving every little setting that can improve my experience in DTTG a chance.