ddim_sample_loop

when I use ddim_sample_loop instead of p_sample_loop, there are two questions for me: 1 ddim does not speed up the inference process, the time consumption is the same as using p_sample_loop. If it is not targeted to accelerate, what dose it do? 2 Can methods for DPM, such as DPM-solver/DDIM, be directly used in DiT?

Thanks for replying!