2. Are there any perl modules which are using XS to get these queries done faster without opening a shell?

There's no need to open shell to read /proc/loadavg. Just read it from perl: 

while(1) {
    open my $la, '<', '/proc/loadavg';
    print <$la>;
    close $la;
    sleep 1;
}

[download]

Upd: script fixed

In reply to Re: get system info using perl by zwon
in thread get system info using perl by saurabh.hirani

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