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This really only affects you if you have your own server(s).
Unless you have really crap servers/hosting and run most or all
of your site under https .... then it is not really an issue.

On the hosting I use with dedicated SSL certs, there is no
noticeable difference in page load/display times whether
browsing sites entirely under https or normally.

SSL acceleration is a method of offloading the processor-intensive public key encryption algorithms involved in SSL transactions to a hardware accelerator. Typically, this is a separate card that plugs into a PCI slot in a computer that contains one or more co-processors able to handle much of the SSL processing.

The most computationally expensive part of an SSL session is the stage where the SSL server (usually an SSL webserver) software is required to decrypt the SSL session key (an asymmetric key) that has been sent to it from the SSL client (usually a web browser), this is known as the SSL handshake. Typically a hardware SSL accelerator will offload processing of the SSL handshake while leaving the server software to process the less intense symmetric cryptography of the actual SSL data exchange, but some accelerators act as a proxy handling all SSL operations and leaving the server seeing only plaintext connections.