DDIM sampler take extremely long time at beginning of training

[ZiboZ]

at the image shows, the DDIM sampler seems run twice at beginning，one is around 1 min and another take about 1 hour. may anyone have a look please! here is my start script:

!(python main.py
-t
--base configs/stable-diffusion/pokemon.yaml
--gpus 4,5,6,7
--scale_lr False
--num_nodes 1
--check_val_every_n_epoch 10
--finetune_from "models/ldm/stable-diffusion-v1/sd-v1-4-full-ema.ckpt"
--n_gpus 2
data.params.batch_size="4"
lightning.trainer.accumulate_grad_batches="1"
data.params.validation.params.n_gpus="1"
)