[Koha] server hang due to opac load

From last one week it observe that when I try to run Koha OPAC on 80 port,

Dear All, I am using Koha 3.22.x on Debain 8. the apache run opac cgi files on their own and lot of process get loaded due to which server load get raised upto 130-140 load and server get hanged. When I run opac on the same server with a port let say 8081, all process worked fine and load of server remain below 1. Can anyone have any idea what wrong with my server or confgiuration?