[superjan]

There has been work done one optimizing regular base64 using SSE:

http://www.alfredklomp.com/programming/sse-base64/

[jpegqs]

I know that. My approach is different: instead of finding the fastest solution to deal with the existing base64 standard, I modify the standard to make it easier to decode. (There are cases when it isn't necessary to follow the standard.)