Quote from: lihuajkl on November 30, 2015, 03:53:35 PM

Sometimes the network is crowd and you need to pay higher than recommended fees to get the transactions confirmed otherwise it will take long time! You could check here cointape.com to calculate the fees.

The network was not congested at all when this happened. The advantage of this attack is that little fee is required to disrupt the networks since the size isn't big. The blocks at that time weren't filled up at all in terms of size but were filled up with the number of sigops. Eg. This transaction https://blockchain.info/tx/9e451c7d53ca42a15b4e55ca67e7defc4d941959255ca6b960f010e623949b51. It doesn't require a high cost if network isn't paying high fees.