DIND Build too slow

How I can improove speed of my build I have runner on dedicated machine with 8 GiG os RAM an 8 CPUs

ivan.skiridomov@worker-01:~$ sudo cat /etc/gitlab-runner/config.toml
concurrent = 1
check_interval = 0

[[runners]]
  name = "worker-01.gitlab.dev.nl.local"
  url = "https://git.mycompany.io/ci"
  token = "720f055bd046d2d1e729b9070cbf5a"
  executor = "docker"
  [runners.docker]
    tls_verify = false
    image = "python:2"
    privileged = true
    disable_cache = false
    volumes = ["/cache"]
  [runners.cache]

this is my .gitlab-ci.yml

make_image:
  stage: make_image
  image: docker
  services:
    - docker:dind
  script:
    - docker login -u $DOCKER_REGISTRY_USERNAME -p $DOCKER_REGISTRY_PASSWORD my_registry
    - docker build -t $CONTAINER_TEST_IMAGE .
    - docker push $CONTAINER_TEST_IMAGE

Build and push to registry takes 20 minutes. Instead of 3 seconds locally cached build and 1 minute fresh --nocache build.

My Dockerfile is

FROM python:2

ENV APP_HOME=/app
ENV APP_PROJ=$APP_HOME/backend

RUN useradd -ms /bin/bash app
RUN mkdir /app

ADD . $APP_PROJ

WORKDIR $APP_HOME
RUN mkdir static logs logs/celery

COPY docker-entrypoint.sh /

RUN apt-get update
RUN cat $APP_PROJ/apt-reqs.txt | xargs apt-get install -y
RUN chown -R app:app $APP_HOME
RUN chmod +x /docker-entrypoint.sh

USER app

EXPOSE 8000
WORKDIR $APP_PROJ
ENTRYPOINT ["/docker-entrypoint.sh"]