pads, you are using a standard compound in race conditions,our shop sets up lots of traga and dutton cars and never use a standard pad, roy is on the same path, start simple. think about what the standard pad was designed for and the maximum temps it can with stand, not much, it will fade very quickly trying to haul up 1500kg traveling at 200km.
there are plenty of great pads mintex, pagid, ebc the list goes on.
rotor condition as roy pointed out also is just as important, keep it simple.