Performance issue when using random generator inside a class

My aim is to create a wrapper around Boost uniform real distribution with Mersenne Twister in order to make it available in a library. So I created a basic class like this:

class mt19937
{
protected:
   boost::random::mt19937 gen_;
   boost::random::uniform_real_distribution<double> real_;
public:
   mt19937(unsigned long s = 5489UL) : gen_(s), real_(0., 1.) {};
   double get() { return real_(gen_); };
};

Running a performance test though, I found out that my class is much slower than a direct call to Boost ojects. In fact, the following code which samples 10 billions of numbers, takes on my machine 30s:

constexpr unsigned long seed = 5489UL;
constexpr size_t iter = 100000;
double x = 0.;

boost::random::mt19937 gen(seed);
boost::random::uniform_real_distribution<double> real(0., 1.);

for (size_t i = 0; i < iter; ++i)
   for (size_t j = 0; j < iter; ++j)
      x = real(gen);

The class mt19937 described above, with the following code, takes around 70s:

mt19937 stduniform(seed);

for (size_t i = 0; i < iter; ++i)
   for (size_t j = 0; j < iter; ++j)
      x = stduniform.get();

Looking at assembler in Windows, in the first case the code executed for x = real(gen) is the following, which seems to me just the call to boost::random::detail::generate_uniform_real and the assignment to x:

00007FF6D14639F0  movzx       r9d,byte ptr [r15]  
00007FF6D14639F4  lea         rcx,[gen]  
00007FF6D14639F9  movaps      xmm2,xmm7  
00007FF6D14639FC  movaps      xmm1,xmm8  
00007FF6D1463A00  call        boost::random::detail::generate_uniform_real<boost::random::mersenne_twister_engine<unsigned int,32,624,397,31,2567483615,11,4294967295,7,2636928640,15,4022730752,18,1812433253>,double> (07FF6D146141Ah)

With the function get() I see the following istructions - it seems to perform some operations on registers that I cannot explain and a jump:

00007FF6D1463B61  movsd       xmm3,mmword ptr [rbp+900h]  
00007FF6D1463B69  lea         rcx,[stduniform]  
00007FF6D1463B6E  movsd       xmm4,mmword ptr [rbp+8F8h]  
00007FF6D1463B76  movaps      xmm2,xmm3  
00007FF6D1463B79  mulsd       xmm2,xmm6  
00007FF6D1463B7D  movaps      xmm1,xmm4  
00007FF6D1463B80  mulsd       xmm1,xmm6  
00007FF6D1463B84  movaps      xmm0,xmm2  
00007FF6D1463B87  subsd       xmm0,xmm1  
00007FF6D1463B8B  comisd      xmm0,xmm7  
00007FF6D1463B8F  jbe         main+2F8h (07FF6D1463B98h)  
00007FF6D1463B91  call        boost::random::detail::generate_uniform_real<boost::random::mersenne_twister_engine<unsigned int,32,624,397,31,2567483615,11,4294967295,7,2636928640,15,4022730752,18,1812433253>,double> (07FF6D14615D7h)  
00007FF6D1463B96  jmp         main+307h (07FF6D1463BA7h)  
00007FF6D1463B98  movzx       r9d,byte ptr [rbx]  
00007FF6D1463B9C  movaps      xmm2,xmm3  
00007FF6D1463B9F  movaps      xmm1,xmm4  
00007FF6D1463BA2  call        boost::random::detail::generate_uniform_real<boost::random::mersenne_twister_engine<unsigned int,32,624,397,31,2567483615,11,4294967295,7,2636928640,15,4022730752,18,1812433253>,double> (07FF6D146141Ah)

Is it possible that a call to a function (that should be inlined) performed 10 billions of times can add this overhead? Do you have any suggestion about the code to increase performance?

I am working in Windows environment and using the compiler vc14 of VisualStudio2015, with Boost 1.7.1. I observed a similar behaviour with gcc4.9 on a Linux machine, where the direct call to Boost takes 30s and the new class takes 45s.

Thanks a lot for your time.