diff --git a/main/config_default/httpd-idds-443-py39-cc7.conf b/main/config_default/httpd-idds-443-py39-cc7.conf
index 8d440270..4922fa16 100644
--- a/main/config_default/httpd-idds-443-py39-cc7.conf
+++ b/main/config_default/httpd-idds-443-py39-cc7.conf
@@ -8,6 +8,7 @@
 
 TimeOut 600
 KeepAliveTimeout 600
+SSLSessionCacheTimeout 600
 
 # Built-in modules
 LoadModule ssl_module /usr/lib64/httpd/modules/mod_ssl.so
@@ -25,11 +26,29 @@ LoadModule gridsite_module /usr/lib64/httpd/modules/mod_gridsite.so
 # #LoadModule wsgi_module /usr/lib64/httpd/modules/mod_wsgi.so
 LoadModule wsgi_module /opt/idds/lib/python3.9/site-packages/mod_wsgi/server/mod_wsgi-py39.cpython-39-x86_64-linux-gnu.so
 
+<IfModule prefork.c>
+StartServers         ${IDDS_SERVER_CONF_MIN_WORKERS}
+MinSpareServers      ${IDDS_SERVER_CONF_MIN_WORKERS}
+ServerLimit          ${IDDS_SERVER_CONF_MAX_WORKERS}
+MaxSpareServers      ${IDDS_SERVER_CONF_MAX_WORKERS}
+MaxClients           ${IDDS_SERVER_CONF_MAX_WORKERS}
+MaxRequestsPerChild  2000
+</IfModule>
+
+<IfModule mpm_event_module>
+StartServers           ${IDDS_SERVER_CONF_MIN_WORKERS}
+MinSpareThreads        ${IDDS_SERVER_CONF_MIN_WORKERS}
+ServerLimit            ${IDDS_SERVER_CONF_MAX_WORKERS}
+MaxSpareThreads        ${IDDS_SERVER_CONF_MAX_WORKERS}
+MaxRequestWorkers      ${IDDS_SERVER_CONF_MAX_WORKERS}
+MaxConnectionsPerChild 2000
+</IfModule>
+
 WSGIPythonHome /opt/idds
 WSGIPythonPath /opt/idds/lib/python3.9/site-packages
 
 <IfModule mod_wsgi.c>
-    WSGIDaemonProcess idds_daemon processes=25 threads=2 request-timeout=600 queue-timeout=600 python-home=/opt/idds python-path=/opt/idds/lib/python3.9/site-packages python-path=/opt/idds python-path=/opt/idds/lib/python3.9/site-packages
+    WSGIDaemonProcess idds_daemon processes=${IDDS_SERVER_CONF_NUM_WSGI} threads=2 request-timeout=600 queue-timeout=600 python-home=/opt/idds python-path=/opt/idds/lib/python3.9/site-packages python-path=/opt/idds python-path=/opt/idds/lib/python3.9/site-packages
     WSGIProcessGroup idds_daemon
     WSGIApplicationGroup %GLOBAL
     WSGIScriptAlias /idds /opt/idds/bin/idds.wsgi
diff --git a/start-daemon.sh b/start-daemon.sh
index 31865f51..cadc96b6 100755
--- a/start-daemon.sh
+++ b/start-daemon.sh
@@ -179,6 +179,21 @@ if [ ! -z "$IDDS_PRINT_CFG" ]; then
     echo ""
 fi
 
+# min number of workers
+if [[ -z "${IDDS_SERVER_CONF_MIN_WORKERS}" ]]; then
+  export IDDS_SERVER_CONF_MIN_WORKERS=25
+fi
+
+# max number of workers
+if [[ -z "${IDDS_SERVER_CONF_MAX_WORKERS}" ]]; then
+  export IDDS_SERVER_CONF_MAX_WORKERS=512
+fi
+
+# max number of WSGI daemons
+if [[ -z "${IDDS_SERVER_CONF_NUM_WSGI}" ]]; then
+  export IDDS_SERVER_CONF_NUM_WSGI=25
+fi
+
 # create database if not exists
 python /opt/idds/tools/env/create_database.py
 # upgrade database