Single CPU cluster is probably not enough to maintain and execute what you want your cluster to do. If you have any containers named dashboard you can probably remove those because they're only for web ui which you can do without.
Other than that, you can check if some unnecessary replicasets/deployments are running by listing them out:
kubectl get deployments/rs
and delete them by using:
kubectl delete deployments/rs <name>
Other than that if you can deploy a bigger node that's always better.