Slow site loading kgdc.org.in

I noticed my site was slowing down even though I run WP Supercache. I particularly see long delays in loading js from an unknown URL http://www.kgdc.org.in/js/jquery.min.php. I switched off all plugins and still face the issue, so I simply guessed it could be in the theme (Aegaeus – happly using it for years now). I edited the header.php from the theme and removed this js code. The site seems to load much quicker without the waiting for kgdc.org.in and I cannot see any difference with the site; all seems to load and function wel. What is/was this part of header.php that impacts my site?
website: http://www.drentsheerlijk.nl

best regards,
Martin