Maybe the payment cutoff time is a factor. Certainly in the UK, under the Payment Services Regulations 2009, the banks are obliged to credit the money as soon as it arrives*. I guess interpretation of the EU regulations may vary from country to country.
Edit: *Well, the same or next business day if the payment arrives after the cutoff time.
On my UK accounts payments are always instant. On my German accounts it has taken up to 3 business days. It kind of sucks.