Are you sure how fast Nero is burning? Nero lies about it's burning speed unless you set a registry key to make it show the correct speed. Edit the following key:

HKEY_CURRENT_USER\Software\Ahead\Nero - Burning Rom\Recorder

Create a DWord value titled:

ShowSingleRecorderSpeed

Set a value of "1". Though in retrospect that may only work for a single drive, not multiple drives.

Alternatively, if you don't want to edit the registry, you can download this self-extracting RAR file I created to automate the process.

http://rockent.brinkster.net/Files/TrueNeroSpeed.exe