  Existing performance comparisons of QUIC and TCP compared an optimized QUIC
to an unoptimized TCP stack. By neglecting available TCP improvements
inherently included in QUIC, comparisons do not shed light on the performance
of current web stacks. In this paper, we can show that tuning TCP parameters is
not negligible and directly yields significant improvements. Nevertheless, QUIC
still outperforms even our tuned variant of TCP. This performance advantage is
mostly caused by QUIC's reduced RTT design during connection establishment,
and, in case of lossy networks due to its ability to circumvent head-of-line
blocking.
