Streaming batch_size=256
100%|█████████████████████████████████████████████████████████████████████| 5000/5000 [00:01<00:00, 2554.43it/s]
(diminishing returns, saturated the GPU)

Example where it's most a slowdown:
thon
class MyDataset(Dataset):
    def len(self):
        return 5000
def __getitem__(self, i):
    if i % 64 == 0:
        n = 100
    else:
        n = 1
    return "This is a test" * n