Hello,

1. How to remove blank spaces between the last element and the footer

We recommend the following:
1. Create an HTML block with the divider http://prntscr.com/jyzyj1 and set margin -40px to the row http://prntscr.com/jyzzze

2. Add this HTML to the Pre-footer area in Theme Settings > Footer.

As for site speed, we have checked the site, visited all the pages we do not see the problem the site is loading well.

Best Regards