Sync mount option makes writing *very* slow

Question

I noticed today one of my external HDDs was writing at 1MB/s, and another at 2MB/s, but both were reading just fine. I've just tracked down the problem. I have been mounting USB HDDs with the sync option, so sudden power loss / disconnection / whatever doesn't cause data loss, however, it had quite an effect on speed. Removing the sync mount option boosted write speed up to 47MB/s.
Is this known/expected/normal behaviour? I'm using 2.6.33.2-1 from testing.

Answer 1

I think that my expectation of how fast I should be able to move files from client to server was wrong.
This post on superuser is about the same complaint (transfers within LAN slower than downloading):
http://superuser.com/questions/528386/l … -downloads
If anyone can confirm that this is normal behavior, I'd be grateful.
This is my setup:
cable modem ---> router -----[wireless connection] ---->client
                                |
                                |
                                -------------{wired connection]------->server
Downloading from internet to the client over wireless is about 1 MB/s. Moving files from client to server is about 500kb/s.