  We study a variant of Vickrey's classic bottleneck model. In our model there
are $n$ agents and each agent strategically chooses when to join a
first-come-first-served observable queue. Agents dislike standing in line and
they take actions in discrete time steps: we assume that each agent has a cost
of $1$ for every time step he waits before joining the queue and a cost of
$w>1$ for every time step he waits in the queue. At each time step a single
agent can be processed. Before each time step, every agent observes the queue
and strategically decides whether or not to join, with the goal of minimizing
his expected cost.
  In this paper we focus on symmetric strategies which are arguably more
natural as they require less coordination. This brings up the following twist
to the usual price of anarchy question: what is the main source for the
inefficiency of symmetric equilibria? is it the players' strategic behavior or
the lack of coordination?
  We present results for two different parameter regimes that are qualitatively
very different: (i) when $w$ is fixed and $n$ grows, we prove a tight bound of
$2$ and show that the entire loss is due to the players' selfish behavior (ii)
when $n$ is fixed and $w$ grows, we prove a tight bound of $\Theta
\left(\sqrt{\frac{w}{n}}\right)$ and show that it is mainly due to lack of
coordination: the same order of magnitude of loss is suffered by any symmetric
profile.
