I think that these few lines (from sub get_html_header() in file: Devel-NYTProf-4.06/bin/nytprofhtml may be where the change would need to be applied. I can't be sure because I believe the code in question is javascript, and I've done very little of that and what I did do, was a long time since:

        format: function(orig) { // format data for normalization 
            // console.log(orig);
            val = orig.replace(/ns/,'');
            if (val != orig) { return val / (1000*1000*1000); } 
            val = orig.replace(/µs/,''); /* XXX use µ ? */
            if (val != orig) { return val / (1000*1000); } 
            var val = orig.replace(/ms/,'');
            if (val != orig) { return val / (1000); }
            var val = orig.replace(/s/,'');  ######## <<<<<<<<<<<<<<
            if (val != orig) { return val; }
            if (orig == '0') { return orig; } 
            console.log('no match for fmt_time of '.concat(orig));
            return orig;
        },
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