That is quite slow. Keep in mind that it might not necessarily be the network causing the bottleneck. Run some performance testing to ensure that it's not the disks attributing to a bottleneck, and you can also check out perf stats for your NICs. Check that your AV software is configured properly. Disable mapi/vapi scanning to see if performance improves.
As far as network bottlenecks go, you should be using 10/100/1000 not 10/100. Ensure you don't have a duplex mismatch anywhere down the line either (switch to switch, client to switch, etc.). Make sure your network cables are good. Update the drivers on your NICs, etc. Check here for more things to tweak relating to a CCR cluster:
http://technet.microsoft.com/en-us/library/bb123996.aspx