I just finished a running Bluespec's regression suite on a version of our tools compiled with ghc 6.8.1. The results were impressive on two fronts: 1. All of our tests (almost 14,000) had the same behavior as with ghc 6.6.1 2. Our Haskell code was roughly 33% faster (relative to ghc 6.6.1). It seems that pointer-tagging made a big difference for our code base (since, if I'm reading the release notes correctly, constructor specialization isn't in yet). We just wanted to take a moment to say that we were pleasantly surprised by ghc 6.8.1 (so much so that we're going to try and use it for released builds sooner than we would have otherwise planned) and to thank everyone involved for the effort they put into it. Thank you, - Ravi Nanavati (and the rest of Bluespec, Inc.)