Disable checksumming to improve local performance?

[Greg Siekas]

Is it possible to disable checksumming?  I'm using rsync with -W,  
whole file, so if a file has changed I don't want to just transfer the  
changes.  The source and destination or local filesystems.
I've noticed that performance in 3.0.6 is slower than 2.6.9.  3.0.6 is  
at ~90MB/sec and 2.6.9 is at ~107MB/sec.   I'm looking for anything  
that can help to improve transfer rates on large files.

thanks,
Greg