[pclmulqdq]

You can do about 100k commits per second, but this also partly depends on the CPU you attach to it. It also varies with how complicated the queries are.

With 100 million DAU, you're often going to have problems with this rate unless you batch your commits. With 100 million user accounts (or MAU), you may be fine.

[direwolf20]

That should be enough for most apps.