Hey there, wish you guys a speedy visa processing. Just wanted to share my bit of the process I know. It is not because of staff shortage that medicals are sent to New Delhi, but because New Delhi is a "Regional Medical Office" for the subcontinent where all the medicals from the neighbouring countries are sent & stored. The respective visa offices have access only to the electronic version of the individual's medical profile rather than the actual file itself. It takes about a month for the visa office to access the file from the RMO after the medicals are done.
Here's a list of all the Regional Medical Offices around the world for processing visas to Canada -
http://www.cic.gc.ca/english/resources/publications/dmp-handbook/appendix-01.asp
All the best!