I recently tested a service that had a Digital Signature system option. At first the Digital Signatures where not enabled, and we were happily testing and getting around 500 ms response times for the service.
Then the Digital Signatures where enabled, and we had to first sign the messages sent, then the server needed to verify the signatures as well.
This turned out to be a major CPU and TIME hog, since on average, regardless of load the verification of the signature took around 200 ms to perform. This made the allover response times increase to around 700 ms for each transaction (200 ms is around 28.5% of 700 ms!). Read More »