The compiler for embedded systems should be fully C++ compliant - certainly the one we use is. We choose to not use templates (much) due to the fact that they often produce quite inefficient and often lead duplicated code in many places (because every time you include the template in one project, it gets a complete set of all the template code compiled into that source file).
But even for PC's there is code that needs to be efficient - your code may not belong in that category, but certainly game developers will "care" if the frame-rate is high or not, and inefficient code will not give good frame-rate.
Likewise, if you are working on a large database-project or some such (e.g you implement the functions in MySQL or some such), any extra time spent there should be avoided.
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Mats