The nginx ingress that comes with microk8s seems to have performance issues when reloading its configuration in presence of a very large number of ingresses.

Using the haproxy ingress gave better results for the OCA instance.

haproxy-ingress-values.yaml:

controller:
  hostNetwork: true
  ingressClass: public
  ingressClassResource:
    enabled: true
    default: true
  config:
    ssl-always-add-https: "true"
    ssl-redirect: "false"

Install/ugprade with haproxy-ingress-upgrade.sh:

helm upgrade haproxy-ingress haproxy-ingress/haproxy-ingress\
  --install\
  --create-namespace --namespace ingress-controller\
  --version 0.13.9\
  -f haproxy-ingress-values.yaml