  In this paper, we revisit the idea to remove Slow Start from congestion
control. To do so, we build upon the newly gained freedom of transport protocol
extendability offered by QUIC to hint bandwidth estimates from a typical web
client to a server. Using this bandwidth estimate, we bootstrap congestion
windows of new connections to quickly utilize available bandwidth. This custom
flow initialization removes the common early exit of Slow Start and thus fuels
short flow fairness with long-running connections. Our results indicate that we
can drastically reduce flow completion time accepting some losses and thereby
an inflated transmission volume. For example, for a typical DSL client, loading
a 2 MB YouTube video chunk is accelerated by nearly 2x. In the worst case, we
find an inflation of the transfer volume by 12% due to losses.
