Tried that one too. Happens exactly the same.

Although, my approach to the issue was that, having tested a few different ways without success, it would actually be me doing something wrong/missing something rather than library's option/func not working as expected.
For that reason, I stopped exploring different options and focused on spotting what Im missing out.

It doesn't happen for me, which version of LWP are you using?

$ perl -MDevel::VersionDump -MLWP -e 1
Perl version: v5.14.1 on MSWin32
Carp               -    1.26
Config             - Unknown
Devel::VersionDump -    0.02
Exporter           -    5.66
Exporter::Heavy    -    5.66
Fcntl              -    1.11
HTTP::Date         -    6.02
HTTP::Headers      -    6.00
HTTP::Message      -    6.03
HTTP::Request      -    6.00
HTTP::Response     -    6.03
HTTP::Status       -    6.03
LWP                -    6.04
LWP::MemberMixin   - Unknown
LWP::Protocol      -    6.00
LWP::UserAgent     -    6.04
Storable           -    2.30
Time::Local        -  1.2300
URI                -    1.60
URI::Escape        -    3.31
XSLoader           -    0.15
constant           -    1.21
overload           -    1.13
strict             -    1.04
vars               -    1.02
warnings           -    1.12
warnings::register -    1.02

l$ perl -MDevel::VersionDump -MLWP -e 1
Perl version: v5.14.2 on linux (BREWED)
Carp               -    1.26
Config             - Unknown
Devel::VersionDump -    0.02
Exporter           -    5.67
Exporter::Heavy    -    5.67
Fcntl              -    1.11
HTTP::Date         -    6.02
HTTP::Headers      -    6.05
HTTP::Message      -    6.06
HTTP::Request      -    6.00
HTTP::Response     -    6.04
HTTP::Status       -    6.03
LWP                -    6.04
LWP::MemberMixin   - Unknown
LWP::Protocol      -    6.00
LWP::UserAgent     -    6.04
Storable           -    2.39
Time::Local        -  1.2300
URI                -    1.60
URI::Escape        -    3.31
XSLoader           -    0.16
constant           -    1.21
overload           -    1.13
strict             -    1.04
vars               -    1.02
warnings           -    1.12
warnings::register -    1.02
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So, you can actually execute that piece of code to dl a large file (~100MB+) and have it copied directly to a file, without using a portion of memory directly proportional to file's size?
If that is the case, then I most definitely must be missing something. Can you spot something wrong with my code?

PS: Didnt know 'Devel::VersionDump'; thanks for the input.

So, you can actually execute that piece of code to dl a large file (~100MB+) and have it copied directly to a file, without using a portion of memory directly proportional to file's size?

I did 38M/135M and , the memory never grew past 10M. For server (never past 12M) I used

 plackup -l localhost:80 -e " use Plack::App::Directory; my $app = Plack::App::Directory->new({ root => q[.] })->to_app; "

Can you spot something wrong with my code?

Nope, I don't see any mistakes but on linux (BREWED) makes me think maybe you're using a fudgy malloc? Kinda unlikely but I've seen folks complain about it :) I'm on win32 so you probably can't compare my Config:)

$ perl "-V:.{0,}alloc.{0,}"
d_attribute_malloc='undef';
d_malloc_good_size='undef';
d_malloc_size='undef';
d_mymalloc='undef';
i_malloc='define';
i_mallocmalloc='undef';
mallocobj='malloc.o';
mallocsrc='malloc.c';
malloctype='void *';
usemallocwrap='define';
usemymalloc='n';
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