ReactOS does not yet support USB drives at all, so you can't boot ReactOS from one. Unless you're talking about putting it all on a virtual machine and dropping that on a flash drive. In that case, ReactOS will be much faster, hands down! That's partly because the kernel is still incomplete, so there's less to load into memory at this point.
I'm still not clear what the goal is. Windows 3.1 would be even faster, if that's all that matters. If you also want a fully functional operating system, ReactOS is still in alpha stage, which means potentially unstable and not recommended for mission critical use. Please use, test, and report on your experience with ReactOS, but don't expect it to be a viable alternative to Windows at this point.
Yes, but please don't reply to spam, since it will look like you're accusing a legitimate post of being spam once the offending message is removed. Just use the "Report this post" button.