use strict;
use warnings;
use diagnostics;
use LWP::UserAgent;
use HTTP::Request;
use HTTP::Response;
use IO::Handle;

my $Proxy_Username='admin';
my $Proxy_Password='adminpw';
my @Proxies = (
    "http://proxy1:23651/proxy-proxy1-proxy/bin/sitemon?doit HTTP/1.0",
    "http://proxy2:23651/proxy-proxy2-proxy/bin/sitemon?doit HTTP/1.0",
    "http://proxy3:23651/proxy-proxy3-proxy/bin/sitemon?doit HTTP/1.0",
    "http://proxy4:23651/proxy-proxy4-proxy/bin/sitemon?doit HTTP/1.0"
);
my @Requests;
for my $URL (@Proxies) { 							# Better outside the loop.
		my $Request = HTTP::Request->new(GET => $URL);
		$Request->referer("http://wizard.yellowbrick.oz");
		$Request->authorization_basic($Proxy_Username,$Proxy_Password);
		push @Requests, $request;
}

STDERR->autoflush(1);  
STDOUT->autoflush(1);  

my $UA = LWP::UserAgent->new();						# No point re-creating $UA each time in the loop
$UA->agent("Mozilla/4.7 [en] (WinNT; I)");			# The parameters don't change. 
$UA->timeout(15);									# Keep them outside the loop.
$UA->max_size(5000);
my $delim	= '--THIS_STRING_NEVER_HAPPENS';

while (sleep 60) { 									# Why 1==1 (just 1 would do) but this is better.
	# No need to call time(), it's the default. 	# No need to name it if you only going to print it.
	print scalar localtime()," --> ";				# As I recently learnt, the scalar is important.
	
	foreach my $Request (@Requests) {				# Note: named loop counter; not my $Request = $_ inside.
		my $Response = $UA->request($Request);
		print "something wrong happened contacting $URL....\n"
			and next if $Response->is_error();		# Not everyone agrees with this syntax

		# everything went ok
		my $Content	= $Response->content();
		
		# Rather than break the data into lines and the loop over the lines, break out the piece you want
		# Rather than use a regex for a static string, use index. 
		my $first			= index( $Content, $delim , 0 ) + length $delim;
		my $second			= index( $Content, $delim , $first );
		
		# I'd be tempted to print out the value of $second-$first, so that you may more closely tailor
		# the max-size parameter. You could also look for a header of X-Content-Range which the user agent
		# adds if the the size of the buffer requested was exceeded (See LWP::UserAgent docs)		
		my $NewContent		= substr( $content, $first, $second );
		
		# Now we have a whole page in $new, we can break just this bit up
		@NewContentArray=split(/\n/,$Content);

		# I'll have to take your word that this does what you need it to do. 
		# The value 14 will possibly need adjusting.
		if ($NewContentArray[14]=~/(>\s)(\d*)(\s<)/) {
			print $2," "; 					 		# get number of active processes
		}
	}
	print "\n";
}