FreeBSD 6.1 6.2 C++ stl set.clear() very slow

[valiy]

FreeBSD  6.2-RELEASE FreeBSD 6.2-RELEASE #0: Mon Jan 15 14:39:55 MSK 
2007     root at valiy:/usr/src/sys/i386/compile/MY  i386

 valiy# g++ test_set.cpp
valiy# ./a.out
filling
clearing
done
alloc time 3.783        clear time 7.987

valiy# g++34 test_set.cpp
valiy# ./a.out
filling
clearing
done
alloc time 3.850        clear time 7.889

valiy# ./a.out
filling
clearing
done
alloc time 4.253        clear time 7.994

valiy# ./a.out
filling
clearing
done
alloc time 3.573        clear time 0.293