HTTPS is great: here’s why everyone needs to use it
The only problem is that many of these issues, mostly technical in nature, are red herrings and can be easily handled with cleverness by an engineering team focused on transmitting its entire application over an encrypted channel. The real issues begin to arise, however, when your application must include assets served by servers which also do not support SSL. We’re going to go over a number of the issues raised by the article, correct some of the more specious arguments, explain how an organization can work with the real constraints, and give some insight into what we consider to be the real barriers to wholesale HTTPS encryption of the Web.
Caching
The article says that one of the things keeping SSL down is that content served over SSL cannot be cached. There’s a lot of confusion about this issue, but the takeaway is that it is indeed very possible to make sure that your content transmitted over SSL is cachable by end users.
There are a few levels of resource caching for most HTTP requests. Client-side browser caching is important and lets browsers avoid making duplicate requests when they already have fresh content. Server-side caching (in proxies, for instance) is important for some users some of the time.