Implement batched GPU transforms #232
Description
> This might be because MONAI transforms are not batched (executed in a loop), and CPU/GPU sync could be taking much longer than the actual compute.
Benchmark of 3D random affine in 6a88ec4 (10 runs, milliseconds):
| Device | MONAI (sequential) | Kornia (batched) | Relative |
|---|---|---|---|
| Zen 2 CPU (1 thread) | 9160 | 3800 | 2.4 |
| Zen 2 CPU (16 threads) | 7320 | 556 | 13.2 |
| A40 GPU | 2620 | 210 | 12.5 |
Originally posted by @ziw-liu in #218 (comment)