Index: openacs-4/packages/acs-tcl/tcl/apm-init.tcl
===================================================================
RCS file: /usr/local/cvsroot/openacs-4/packages/acs-tcl/tcl/apm-init.tcl,v
diff -u -r1.3 -r1.3.2.1
--- openacs-4/packages/acs-tcl/tcl/apm-init.tcl	7 Aug 2017 23:47:59 -0000	1.3
+++ openacs-4/packages/acs-tcl/tcl/apm-init.tcl	2 Sep 2021 17:10:27 -0000	1.3.2.1
@@ -12,6 +12,18 @@
 nsv_array set apm_package_info [list]
 nsv_set apm_properties reload_level 0
 
+namespace eval apm {
+
+    # Cache the singleton_p property of all packages.
+    db_foreach get_singleton {
+        select package_key, singleton_p
+        from apm_package_types
+    } {
+        set ::apm::package_singleton_p($package_key) $singleton_p
+    }
+
+}
+
 # Local variables:
 #    mode: tcl
 #    tcl-indent-level: 4
Index: openacs-4/packages/acs-tcl/tcl/apm-procs.tcl
===================================================================
RCS file: /usr/local/cvsroot/openacs-4/packages/acs-tcl/tcl/apm-procs.tcl,v
diff -u -r1.114.2.32 -r1.114.2.33
--- openacs-4/packages/acs-tcl/tcl/apm-procs.tcl	30 Mar 2021 15:41:18 -0000	1.114.2.32
+++ openacs-4/packages/acs-tcl/tcl/apm-procs.tcl	2 Sep 2021 17:10:27 -0000	1.114.2.33
@@ -349,7 +349,6 @@
     return [nsv_get apm_package_url_resolution $package_key]
 }
 
-
 ad_proc -private apm_package_load_libraries_order {
     package_key
 } {
@@ -358,6 +357,23 @@
     return [nsv_get apm_package_load_libraries_order $package_key]
 }
 
+ad_proc -private apm_package_singleton_p {
+    package_key
+} {
+    @return boolean telling whether a package is a singleton or not
+} {
+    if {[info exists ::apm::package_singleton_p($package_key)]} {
+        return $::apm::package_singleton_p($package_key)
+    } else {
+        # Fallback for code executed when the cache has not been
+        # populated, or for new packages before restart.
+        return [db_string check_singleton {
+            select singleton_p from apm_package_types
+            where package_key = :package_key
+        } -default f]
+    }
+}
+
 ad_proc -public apm_version_loaded_p { version_id } {
 
     Returns 1 if a version of a package has been loaded and initialized, or 0 otherwise.
Index: openacs-4/packages/acs-tcl/tcl/parameter-procs.tcl
===================================================================
RCS file: /usr/local/cvsroot/openacs-4/packages/acs-tcl/tcl/parameter-procs.tcl,v
diff -u -r1.26.2.3 -r1.26.2.4
--- openacs-4/packages/acs-tcl/tcl/parameter-procs.tcl	5 Jan 2021 17:10:17 -0000	1.26.2.3
+++ openacs-4/packages/acs-tcl/tcl/parameter-procs.tcl	2 Sep 2021 17:10:27 -0000	1.26.2.4
@@ -261,11 +261,7 @@
     #    packages.
     #
     if {$value eq ""} {
-        if {[db_string check_singleton {
-            select 1 from apm_package_types
-            where package_key = :package_key
-            and singleton_p = 't'
-        } -default 0]} {
+        if {[apm_package_singleton_p $package_key]} {
             set value [parameter::get \
                            -localize=$localize_p \
                            -boolean=$boolean_p \