The advantage of C++ is that you can completely control memory layout. Because of the way modern CPU's work, making sure that data is aligned to minimize cache

The advantage of C++ is that you can completely control memory layout. Because of the way modern CPU's work, making sure that data is aligned to minimize cache misses is super important when writing high performance code. But it is only important for maybe 5% of the code (the low level vertex and texture management code). The rest you can write in almost any language.