The reason why there aren't any performance leaks yet is because the drivers haven't been provided yet. Basically, the very few reviewers who have a GeForce RTX 2080 and/or GeForce RTX 2080 Ti can't test them yet.
The rest of reviewers will not get samples until early September.
As a bonus, here's a block diagram of the NVIDIA TU102 GPU. The scheme confirms the Quadro RTX 6000 and 8000 use the full version of the chip, with all 4608 CUDA cores enabled. The GeForce RTX 2080 Ti is a cut-down version with 4352 CUDA cores. The slide also reveals TU102 has 576 Tensor cores, 72 RT cores, 36 Geometry Units, 288 TMUs, 96 ROPs, and a 384-bit memory bus with 14GHz GDDR6 memory.