I noticed an unneeded write to dr7 in the signal handling path for x86.  
We only need to write to dr7 if there is a breakpoint to re-enable, and 
MOVDR is a serializing instruction, which is expensive.  Getting rid of 
it gets a 33% faster signal delivery path (at least on Xeon - I didn't 
test other CPUs, so your gain may vary).

Cheers,

Zachary Amsden
zach@vmware.com