Performance decreasing

Ever since 1.6.4 performance has been decreasing..

Back in 1.6.4, performance was excellent, achieving 25+fps with fancy graphics and far viewing distance..
But ever since 1.6.4+ performance has been crazily stupid! with single digit fps, running fast graphics, low (2-3 chunks) viewing distance and no smooth lighting..

I tried tweeting some minecraft developers to see if they would work on performance, but no reply so I thought I would post on here to get some attention..

And yes I know this would be a duplicate of many other ones..
Just like to get a minecraft coder to help.