Problems with appointment calendar script

[goldpompon]

Hello!
One script loads slowly for about 5 seconds. Is it possible to speed up the process? Displayed incorrectly in responsive design. How can this be fixed?

Link to calendar: http://www.klavierstimmer.com/terminbuchung.html

Thank you in advance for your help.

[BaconFries]

One script loads slowly for about 5 seconds

What script and were do we need to look? Note if using any third party script(s) please remove them as they could cause conflicts with the already generated script(s) of the program and see if that resolves this.

[Pablo]

It looks like the calendar is script loaded inside an inline framer
This means that WWB has no affect on the behavior and performance of the script.