db = SqliteDatabase(':memory:')
with db.batch_commit(10):
    for n in range(0, 1234):
        Model.create(**...)

Every N'th model creation commits the transaction, the equivalent Python without batch_commit is:

with db.manual_commit():
    db.begin():
    for n, row in enumerate(...):
        Model.create(**row)
        if n % 100 == 0:
            db.commit()
            db.begin()
    db.commit()

Having a batch_commit would make it easier/simpler to make batch inserts faster.

Alternatively there is Model.insert_many, but to create multiple linked models at the same time the batch_commit method could be useful.

Using db.atomic() works unless you have a large number of items to insert, in that case periodic commits are used to ensure data is synchronised to disk, e.g.:

with db.atomic():
    for row in data:
        row.update(defaults)
        Model.create(**row)

it's probably easier to do it using a batch iterator instead of modifying peewee:

for work in batch(rows, n=1234):
    with db.atomic():
        for row in work:
            Model.create(**row)

Feel free to close, I answered own question...