diff --git a/runbot/models/runbot.py b/runbot/models/runbot.py
index 82b9b929..a0c90dee 100644
--- a/runbot/models/runbot.py
+++ b/runbot/models/runbot.py
@@ -9,6 +9,7 @@ import shutil
 
 from contextlib import contextmanager
 from requests.exceptions import HTTPError
+from subprocess import CalledProcessError
 
 from ..common import fqdn, dest_reg, os
 from ..container import docker_ps, docker_stop
@@ -367,6 +368,17 @@ class Runbot(models.AbstractModel):
         if ignored:
             _logger.info('docker (%s) not deleted because not dest format', list(ignored))
 
+    def _git_gc(self, host):
+        """
+        cleanup and optimize git repositories on the host
+        """
+        for repo in self.env['runbot.repo'].search():
+            try:
+                repo._git(['gc', '--prune=all', '--quiet'])
+            except CalledProcessError as e:
+                message = f'git gc failed on host {host} with exit status {e.returncode} and message "{e.output[:30]} ..."'
+                self.warning.create({'message': message})
+
     def warning(self, message, *args):
         if args:
             message = message % args
diff --git a/runbot_builder/builder.py b/runbot_builder/builder.py
index 430df060..8000a481 100755
--- a/runbot_builder/builder.py
+++ b/runbot_builder/builder.py
@@ -17,6 +17,8 @@ class BuilderClient(RunbotClient):
             self.env['runbot.runbot']._docker_cleanup()
             self.host.set_psql_conn_count()
             self.host._docker_build()
+            self.env['runbot.repo']._update_git_config()
+            self.git_gc()
         return self.env['runbot.runbot']._scheduler_loop_turn(self.host)
 
 
diff --git a/runbot_builder/leader.py b/runbot_builder/leader.py
index 6a21ced9..6795e9d4 100755
--- a/runbot_builder/leader.py
+++ b/runbot_builder/leader.py
@@ -10,7 +10,13 @@ class LeaderClient(RunbotClient):  # Conductor, Director, Main, Maestro, Lead
         self.pull_info_failures = {}
         super().__init__(env)
 
+    def on_start(self):
+        self.env['runbot.repo'].search([('mode', '!=', 'disabled')])._update(force=True)
+
     def loop_turn(self):
+        if self.count == 0:
+            self.env['runbot.repo']._update_git_config()
+        self.git_gc()
         return self.env['runbot.runbot']._fetch_loop_turn(self.host, self.pull_info_failures)
 
 
diff --git a/runbot_builder/tools.py b/runbot_builder/tools.py
index 64b02c5e..31a8a225 100644
--- a/runbot_builder/tools.py
+++ b/runbot_builder/tools.py
@@ -4,8 +4,10 @@ import logging
 import os
 import sys
 import threading
+import random
 import signal
 
+from datetime import datetime, timedelta
 from logging.handlers import WatchedFileHandler
 
 LOG_FORMAT = '%(asctime)s %(levelname)s %(name)s: %(message)s'
@@ -24,6 +26,7 @@ class RunbotClient():
         self.host = None
         self.count = 0
         self.max_count = 60
+        self.next_git_gc_date = datetime.now() + timedelta(minutes=random.randint(5, 15))
 
     def on_start(self):
         pass
@@ -80,6 +83,13 @@ class RunbotClient():
     def sleep(self, t):
         self.ask_interrupt.wait(t)
 
+    def git_gc(self):
+        """ git gc once a day """
+        if datetime.now() > self.next_git_gc_date:
+            _logger.info('Starting git gc on repositories')
+            self.env['runbot.runbot']._git_gc(self.host)
+            self.next_git_gc_date = datetime.now() + timedelta(hours=2, minutes=random.randint(0, 59))
+            _logger.info('Next git gc scheduled on %s', self.next_git_gc_date)
 
 def run(client_class):
     # parse args