Rendering streamline data

I want to use unity to visualize streamline data from CAE analysis software and use GL in OnPostRender() to link the points one by one in a single streamline by drawing segments.

  void OnPostRender()
     {
         calcolor m_color = new calcolor(max_v, min_v);
         CreateLineMaterial();
         // set the current material
         GL.PushMatrix();
         lineMaterial.SetPass(0);
         GL.Begin(GL.LINES);
         for (int i = 0; i < m_stream.v_stream.Count; i++)
         {
             for (int j = 0; j < m_stream.v_stream[i].v_node.Count - 1; j++)
             {
                 GL.Color(m_color.getcolor(m_stream.v_stream[i].v_node[j].v));
                 GL.Vertex3(m_stream.v_stream[i].v_node[j].x, m_stream.v_stream[i].v_node[j].y, m_stream.v_stream[i].v_node[j].z);
                 GL.Color(m_color.getcolor(m_stream.v_stream[i].v_node[j + 1].v));
                 GL.Vertex3(m_stream.v_stream[i].v_node[j + 1].x, m_stream.v_stream[i].v_node[j + 1].y, m_stream.v_stream[i].v_node[j + 1].z);
             }
         }
         GL.End();
         GL.PopMatrix();
     }

The effect looks like this:

However, the data is too large and even after pre-processing it still contains more than 180,000 points. So the rendering speed is less than 10 FPS.

How to speed up rendering of a large amount of lines? Does unity have any mechanism like double buffering in OpenGL?