I thought that was because visual basic/c++/c# all used the same base compiler.
Unmanaged C++ code is completely different from the ".NET" languages like VB.NET / C++.NET / C#.NET.
Even though JIT compilers like C# and Java can perform some optimizations that C++ can't, unmanaged C++ compilers have always been able to produce much more efficient code, which means overall the resulting EXEs will be considerably faster on just about any processor.
If you really think JIT is faster than unmanaged C++, do a search for benchmarks. You'll find that C#/Java is almost always slower than C++. JIT certainly helps, but obviously not enough to make up the difference for it's lack of in-depth optimizations which C++ compilers have.