Via using Cloudflare, my site is becoming slow

Hi Team,
Via using Cloudflare, my site is becoming slow although, I have turned on all the options and proxy too. Please let me know how can I sort this issue and increase the performance.
My site is https://hobo.video/, I am using Digital Ocean server.

Please help!

At first sight, when I open your Website, I see some errors appear in my Developer Console like 400 for admin-ajax.php, etc.
Otherwise, you have got enough resources to load up like videos on scroll or “on first shown up”, etc. approx. 8MBs in 16.8 seconds, dom 571ms, load 5.73 seconds

Hi,
Yeah, 400 for admin-ajax.php is showing, I tried to resolve that but it shows always although everything is working properly in my site.

On the other hand, when I try proxy, my site speed is slower. I am not getting the reasons though. I checked on GTMatrix, pingdom, Lighthhouse, webpagetest too but all of them show speed issues.

on the other hand, when I enable proxy, results are worst on all the performance tools.

Is there any other way to improve the performance?