How does EV green extended validation SSL certificate affects the
speed of my web site (if at all) comparing to a regular SSL?
EV SSL certificate doesn’t affect on website loading speed and works same as non-EV SSL certificate. In fact all SSL certificates come with same 256-bit encryption and 2048-bit root key encryption, but there are difference between the verification processes which puts assurance to your website and inspires web users to deal with.
When CA receive certificate request from applicant, they will check legal, physical and operational existence of the entity by confirming official records like incorporation and business licensing information and requester has special privileges to use the domain.
Once EV SSL certificate is installed on site, it will enable “Your Company Name in the Green Bar” which is most visible sign of security and authentication and help to identify phishing sites.
Also, my provider only allow the EV green certificates to be on the
root (no sub domains or wildcard *. allowed). Is that normal?
All CAs has to follow CA/Browser Forum guideline to issue digital certificate and according rules “Wildcard certificates are not allowed for EV Certificates”.
Can I mix EV green for the root and regular SSL for all sub domains
You cannot get EV SSL certificate for .mydomain.com, because of asterisk () refers unlimited numbers in wildcard terms.
Some certificate providers enable SAN features and allow adding multiple sites or sub-domains with their EV SSL certificate that you can get EV Multi Domain SSL certificate for your sites or/and sub-domains. At the time of ordering certificate, you need to select numbers of subject alternative names and add specify domains and/or host names.
You can also obtain EV SSL certificate for root domain and wildcard SSL certificate for *.mydomain.com. In that case, you need to manage two individual certificates and green bar will not be enabled on sib-domains.