A direct sysread call seems to be >2x faster:

$ ls -sh bigfile.txt
2.8G bigfile.txt

$ cat direct_sysread.pl

use Fcntl qw(:DEFAULT);
use Symbol;

my $file = shift @ARGV;

my $fh = gensym;
sysopen $fh, $file, O_RDONLY;
my $content;
sysread $fh, $content, -s $file;

$ cat file_slurp.pl

use File::Slurp;

my $file = shift @ARGV;
open my $fh, "<", $file or die $!;

my $content = read_file ($file);

$ time direct_sysread.pl bigfile.txt

real    0m1.785s
user    0m0.008s
sys     0m1.776s

$ time file_slurp.pl bigfile.txt

real    0m4.994s
user    0m0.924s
sys     0m4.052s
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citromatik

You could try Sys::Mmap::Simple. It doesn't really load the file, but for some applications, the end result is the same, and it should be much faster for big files.

In Linux you have mmap which is a system function built just for that purpose,of course there are wrappers in Perl that do that for you,like the one mentioned above.

MMAP(2)                                                          Linux
+ Programmerâs Manual                                                 
+        MMAP(2)

NAME
       mmap, munmap - map or unmap files or devices into memory

DESCRIPTION
       mmap()  creates  a new mapping in the virtual address space of 
+the calling process.  The starting address for the new mapping is spe
+cified in addr.
       The length argument specifies the length of the mapping.
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What I was planning to do is to load a particular file into memory, and then open that scalar as a file handle so as to do repeated file operations on it (ideally for performance improvements).
But the way it seems to be working out, it doesn't seem to work... is there a better way?

If this is the case, you're lucky it only takes 10 minutes to read it into a scalar! Symptom to look for: merciless disk thrashing while the file is read to the scalar.

Solution: don't do that! Process the file in pieces.

my $size = -s FILE;
my $giant = ' ' x $size;
print "Read ", read(FILE,$giant,$size,0)," of $size bytes";
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