In libstdc++ 4.4.3-4ubuntu5, getline() is extremely slow, taking around 23us of
user time per line on an Intel T9300 processor. By contrast, fgets() takes
about 0.3us per line. 

Calling ios::sync_with_stdio(false) before the loop start reduces the time per
line to around 0.3us, on par with fgets(). This suggests that the problem is
with the stdio synchronisation code.

           Summary: ifstream::getline() is extremely slow
           Product: gcc
           Version: 4.4.3
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: libstdc++
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: tstarling at wikimedia dot org
 GCC build triplet: i486-linux-gnu
  GCC host triplet: i486-linux-gnu
GCC target triplet: i486-linux-gnu

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