In Germany, where 3 out of 4 retail transactions are made in cash, the German Central Bank undertook a study on speed and cost by transaction type. They compared cash transactions against credit card, direct debit, and girocard payments and the results, published in February 2019 make for interesting reading especially in light of the recent Access to Cash Review report published in the United Kingdom.
Conclusions
The report concluded that cash payments are 7 seconds faster than card payments that require a PIN entry, 16 seconds faster than card payments requiring a signature and 50 euros cheaper on average than card payments.
The full Bundesbank report can be read here: