I open a filehandle to ffmpeg for that:

package External::FFmpeg;
use parent 'Class::Accessor';
__PACKAGE__->mk_accessors(qw(width height depth pid stream texture_id 
+file));

sub spawn {
    my ($self,$cmd) = @_;
    my $pid = open my $stream, $cmd
        or die "Couldn't spawn '$cmd': $!/$?";
    binmode $stream;
    return ($pid,$stream)
};

sub DESTROY {
    if (my $pid = $_[0]->pid) {
        kill 9, $pid
    };
};

package Target::FFmpeg;
use strict;
use parent -norequire => 'External::FFmpeg';

sub new {
    my ($class,%args) = @_;
    my $file = delete $args{filename};
    my $width = delete $args{width} || 352;
    my $height = delete $args{height} || 288;
    my $in_width = delete $args{in_width} || $width;
    my $in_height = delete $args{in_height} || $height;


    my $depth = 3;

    my ($pid,$stream) = $class->spawn(qq{| bin\\ffmpeg-old.exe -y -f r
+awvideo -pix_fmt rgb24 -s ${in_width}x${in_height} -i "-" -f mpeg2vid
+eo -s ${width}x${height} "$file"});
    my $self = $class->SUPER::new({
        width => $width,
        height => $height,
        depth => $depth,
        stream => $stream,
        pid => $pid,
        %args,
    });

    $self
};
[download]

Then I just print each frame (in RGB-format) to the filehandle and let ffmpeg work its magic. You could also try to get FFMpeg to compile+install, but I found using a binary far more convenient.

However, since you already are using ImageMagick to generate the frames(and don't care about sound), I would dig deep into it's docs and examples to find a way with it. IM supports writing to Perl filehandles, in memory images(blobs), and the avi format..... so there may be a way. The problem with IM is the docs are so scattered and unorganized. You may be able to open an animated gif as a blob in memory, write to it, and when done change it's -magick option to avi, then print it. You really have to experiment with IM to get the right combination to work as intended.

I would also look at mencoder (not Perl but it is widely used).

It has a couple of drawbacks (for example losing data on power outage), but it's a very simple solution for performance problems with temporary files.