"Hand over" from cloudflare DNS to Webserver (Drupal) takes 2,5 seconds

dns

#1

the handover from the cloudflare dns to our web server takes 2,5 seconds. Our webserver runs drupal with a plesk system.

I the cloudflare we simply map the domain to the IP with A record (e.g. claimflights.de points to IP xxxx).

Probably a problem of drupal or plesk?
How can we make this faster? Where to start?