Not an area where I have much expertise, but sounds like the original 
compiler was poorly done, and a lots of patches call optimizers are 
added. I would think a good compiler, would do a good job, based on 
individual lines or small groups of lines like a loop of code, and the 
optimizer would look at more of a macro view, to eliminate duplicate 
instructions, etc., say where a value is already in a register.

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