8 years, 1 month ago.

Exceptions are disabled in mbed, so no need to worry about that. Destructors are only called when you actually destruct something, they take a bit of memory but nothing significant.

Performance sacrifice is probably 90% that the basic C(++) stuff that is included (also because the mbed lib uses error messages, which uses printf, which forces it to include all the stdio stuff) consumes alot of memory. So on small devices if you have very little code, you can still require quite some memory. Of course if you actually start using printfs yourself, the extra cost is small.

Overall it depends mainly on how you do stuff. The Serial is not the fastest for example due to it using stdio functions. Or SPI cannot sent stuff on full speed using the mbed lib because it always needs to wait on the transaction to be finished, because it returns the read value. So if you only want to send, it still waits until the previous transaction is done, then it returns that value, and then the overhead of the next write action starts, meaning at high SPI frequencies you start losing performance. But this is no a C++ thing, but an mbed lib thing. There are some user libs that work around this for example.

Also for example https://developer.mbed.org/users/Sissors/code/FastIO/ (shameless self promotion) uses C++ features (templates) that result in performance that will be hard to much with plain C code.