Many of these features are very difficult to use in a useful way in a static context (e.g. at compile time) because the performance gains mostly come from takin

Many of these features are very difficult to use in a useful way in a static context (e.g. at compile time) because the performance gains mostly come from taking advantage of dynamic context. Speculative execution and out of order execution for example are mostly useful because you don't know at compile time exactly what data your code is processing or what CPU it is running on, what function / context you are being called from, what is in cache and what isn't, etc. The SPUs on the PlayStation 3 were an experiment in user managed caches and that proved to be a difficult thing to make effective use of even in games where you know more context than a lot of code can assume.