doubles and compute shaders

I have a compute shader I use to crunch the n-body gravity calculations for my project. when I use all floats in the shader, it runs fine and can process the gravity calculations of 10,000 objects in about 8 ms. However. I can't use floats because part the gravity equation ((G x mass1 x mass2) / d^2) can produce a number greater than what floats can hold with 2 sun sized masses. This leads me to need to use doubles for that part of the calculations. This wouldn't be a problem, except it seems to SEVERELY increase the time it takes to execute the shader for 8 ms to 130 ms. Any input is appreciated.

 [numthreads(256,1,1)]
 void GravityComp (uint3 id : SV_DispatchThreadID)
 {
     uint ind = id.x;
     float2 gravResult = float3(0, 0);
     for (uint i = 0; i < (uint)numAsteroids; i++) {
         if (ind == i)
             continue;
         float distance = Distance(dataIn[ind].xy, dataIn[i].xy);
         double G = (double)0.0000000000667408;
         double m1 = (double)dataIn[ind].z; // mass
         double m2 = (double)dataIn[i].z; // mass
         double newt = (G * m1 * m2) / (double)pow(distance, 2);
         float acc = (float)(newt / m1);
         float2 dir = -normalize(dataIn[ind].xy - dataIn[i].xy);
         float2 grav = dir.xy * acc;
         gravResult.xy = gravResult.xy + grav.xy;
     }
 
     dataOut[ind].xy = gravResult.xy;
 }