When configuring/troubleshooting QOS class settings up to 1 min to see the results in image/table is way too long for me so I looked how to set it lower.
HowTo:
edit
/srv/web/ipfire/html/include/rrdimage.js
search for
Determine auto reload interval
5 lines below you’ll find
case 'hour':
interval = 60;
interval = 60; is what you’re looking for, change it to 10 or what you like.
You might want to restore the original setting (60) after finishing!
HTH!