This is actually something the ISO C++ committee is looking at.<p>See <a href="https:&#x2F;&#x2F;isocpp.org&#x2F;std&#x2F;the-committee" rel="nofollow">https:&#x2F;&#x2F;isocpp.org&#x2F;std&#x2F;the-committee</a> - SG12<p>An example of this is P0145R0 which specifies the previously unspecified order of evaluation.<p>See <a href="https:&#x2F;&#x2F;isocpp.org&#x2F;blog&#x2F;2015&#x2F;11&#x2F;kona-standards-meeting-trip-report" rel="nofollow">https:&#x2F;&#x2F;isocpp.org&#x2F;blog&#x2F;2015&#x2F;11&#x2F;kona-standards-meeting-trip-...</a><p>Apparently, the performance difference is expected to be zero on currently popular architectures and around 1% on older architectures.