[Bug libstdc++/63466] sstream is very slow

[andi-gcc at firstfloor dot org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=63466

--- Comment #2 from Andi Kleen <andi-gcc at firstfloor dot org> ---
Looking at the profile there's plenty of room for optimization. e.g. not using
getc/ungetc, but directly accessing the buffer, or maybe even some kind of
template specialization.

With the variables pulled out it's faster, but still a lot slower than C:

% time ./a.out < testfile 
real    0m0.400s
user    0m0.397s
sys    0m0.002s
% time ./tstream-c < testfile

real    0m0.033s
user    0m0.028s
sys    0m0.004s