Load time of websites increased after CARP

[jwnetwerk]

Hi.

I created a pfSense CARP cluster consisting of 2 nodes.
Behind the CARP cluster there is a webserver. Through the pfSense firewall I configured NAT (port 80) to that webserver.

When monitoring the response (load time) of the websites from that webserver, the average load time was about 250msec before the use of CARP.
Now with CARP in place the average load time has increased to 1500msec.

I can't figure out why websites load much slower when CARP is in place.
Can anyone shine some light on this?

Some tech specs.
pfSense version: 2.3.3-RELEASE-p1
Each pfSense has it own WAN IP and a third one is used for CARP (access IP for the website, outside)
Each pfSense has it own class C local IP and a third for CARP (gateway for the internal webserver)
CARP status is okay, one node master the other slave. no errors are shown.

Thanks.