Displaying progress in the console

[jmurphy]

Some of the processes in PhotometricMosaic need to provide progress feedback to the user.
My current solution:

let lastProgressPc;
function progressCallback(count, total){
    if (count === 0){
        console.write("<end>   0%");
        lastProgressPc = 0;
        processEvents();
    } else {
        let pc = Math.round(100 * count / total);
        if (pc > lastProgressPc && (pc > lastProgressPc + 5 || pc === 100)){
            console.write(format("\b\b\b\b%3d%%", pc));
            lastProgressPc = pc;
            processEvents();
        }
    }
}

This works, but it is slow. I have therefore had to limit it to showing increments of 5%.
Is there a better way of doing this?
Thanks
John Murphy