Another factor is predictability. When you write a line of code in a low-level language like C, you have a reasonably accurate approximation of what the machine is actually going to do for you at that point. Moreover, things like memory management are manual and explicit, and you have a reasonably good idea of when they happen and how long they take. In comparison, a lot of higher languages have a significant and not necessarily predictable overhead in the runtime and/or VM.

Uhm performance?

Could you be a little more specific? What makes C++ faster than, say, Visual Basic 6? Just curious.

C is designed and optimized to be very close to the hardware, in fact it's called high-level assembler. You can access specific hardware features directly. C++ is the OO version of C (yes I know this is an oversimplification). Other languages, like for example Java creates a logical layer (known as the java virtual machine or JVM) which adds more complexity and makes it harder to tweak your code to fit the particular hardware.

C for performance. If you need better abstractions (generics, OO, etc) you can switch to C++.

They don't have garbage collection. C++ is still the most capable no-garbage-collection language.

OpenGL/DirectX APIs are the reason

because they are the best languages.