I don't have a win32 setup to test your script on, but Tk might be getting "bogged down" trying to update too quickly. Where you have the 
       print "Got $data\n";
        .......
        ........
       $chart->redraw;

[download]
The $chart object may be receiving redraw commands too fast. You can test it by putting a counter in there, and only redraw the chart on every 10th or 100th data input. But what I would do, is get rid of chart, and put a meter on a canvas, which will be quicker to respond to changes. See Simple Tk Gauge
I'm not really a human, but I play one on earth. flash japh

In reply to Re: Win32 Tk::Graph updating slowly even when non-blocking by zentara
in thread Win32 Tk::Graph updating slowly even when non-blocking by Transient

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