Extremely slooooow __sys_ftruncate?

In the process of helping to debug a problem with gcc-4.4.0
(actually a gfortran problem), I run gprof on the executable.
The profile shows that __sys_ftruncate is extremely slow.

  %   cumulative   self              self     total           
 time   seconds   seconds    calls  ms/call  ms/call  name    
 85.6       6.05     6.05    51830     0.12     0.12  __sys_ftruncate [2]
  5.6       6.44     0.40        0  100.00%           .mcount (101)
  1.7       6.56     0.12    51872     0.00     0.00  _lseek [5]
  1.6       6.67     0.11    52055     0.00     0.00  sigprocmask [6]
  0.8       6.73     0.06   103687     0.00     0.00  memset [14]
  0.4       6.76     0.03      488     0.06     0.06  __sys_write [18]
  0.4       6.79     0.03        0  100.00%           formatted_transfer_scalar 

time ./z
     184.21 real         0.98 user         6.57 sys

This program should finish well under 184 seconds.  The same program
and exact same gcc/gfortran source on linux shows 
 real    0m0.555s    user    0m0.103s    sys     0m0.452s 

Is __sys_ftruncate known to have performance problems?

-- 
Steve