Timing question with higher accuracy

This jQuery might help
// Declare variables for the start and end times
var startTime1, endTime1, startTime2, endTime2;

// Start timer for Scale 1 when the page loads
$(document).ready(function(){
startTime1 = new Date();
});

// Stop timer for Scale 1 when the user clicks the next button
$("#NextButton").click(function(){
endTime1 = new Date();
// Calculate the time spent on Scale 1
var timeSpent1 = endTime1 - startTime1;
// Store the time spent on Scale 1 in a custom variable
Qualtrics.SurveyEngine.setEmbeddedData("time_scale1", timeSpent1);
// Start timer for Scale 2
startTime2 = new Date();
});

// Stop timer for Scale 2 when the user clicks the next button
$("#NextButton").click(function(){
endTime2 = new Date();
// Calculate the time spent on Scale 2
var timeSpent2 = endTime2 - startTime2;
// Store the time spent on Scale 2 in a custom variable
Qualtrics.SurveyEngine.setEmbeddedData("time_scale2", timeSpent2);
});