In such cases, signing an additional 100 transactions would only require an extra 6400 bytes. Even with a slow connection speed of 100KB/s, this can be transferred in just 64ms, with latency being the dominant factor.

Regarding Replace-By-Fee (RBF), it has a default minimum incremental relay fee of 1sat/vByte. By utilizing the 100 pre-signed transaction variants solely for signing every possible minimum incremental relay, a range of 1sat/vByte to 100sat/vByte can be covered. This range is deemed sufficient to ensure that these transactions get mined for any block throughout Bitcoin's entire modern history.

On the other hand, Child Pays for Parent (CPFP) requires two transactions and therefore additional bytes. Unless dealing with very large transactions in low-fee environments, there are no circumstances where CPFP outperforms RBF.

For more information on this topic, you can visit Peter Todd's website at https://petertodd.org or contact him via email at 'peter'[:-1]@petertodd.org.