By design, HTTPS is slower than HTTP. Considering Google’s focus on speed, does that mean my site will be penalized if I switch to HTTPS?
No, I wouldn’t worry about that. In fact, it can be a very good idea to switch your site to HTTPS. HTTPS, or SSL, is a secure version of HTTP that encrypts things between your browser and the web server. So that keeps your boss, or your ISP, or your government from snooping on whatever is happening on that connection, unless they can do some crazy Mission Impossible, man-in-the-middle attack. And those are relatively rare. But let’s get back to the question.
There is a certain amount of encryption overhead that has to happen, because HTTPS is encrypted. But there’s a lot of unnecessary slowness. So a lot of the people on the Google Chrome team have been working on different protocols. SPDY is one. And also, I think False Start might be the name of another one, where instead of having to set up the connection, and then have an acknowledgment, and set up the connection in order to be able to send the data in encrypted ways, you could just send the data as encrypted immediately. HTTPS can be a really good thing for users. And so there’s a lot of work ongoing to sort of say “OK, people haven’t really paid attention to how to make SSL or how to make HTTPS fast.” And it turns out there’s a lot of low hanging fruit there. And some of it might be a fair amount of work, but it’s probably worth doing.
I would not worry about being penalized. Only like one in 100 searches, which means one in 1,000 websites, is so low on page speed, that it actually affects its ranking, whereas HTTPS can be a really good thing for users. So if you do a search for PayPal, for example, you’ll see that they use the HTTPS version. We’ve looked through our indexing code, and we’ve tried to make sure that any time where someone might want to use an HTTPS version of their site, they won’t be disadvantaged. We’re going to continue to be looking through that, making sure that everything should run smoothly on our side.
by Matt Cutts - Google's Head of Search Quality Team