I'm playing around with a simple program that fills a buffer and writes that to disk. The first variant is strange since it becomes much more than twice as slow, when the test runs twice: http://code.haskell.org/storablevector/speedtest/SpeedTestExpSlow.hs The second variant is strange, because if I use allocaArray instead of allocaBytes then it crashes. However, when I run the test twice, it works. http://code.haskell.org/storablevector/speedtest/SpeedTestExpCrashAllocaArra...