Upgrade core to have lazy-loading option for Fields, Templates, Field…

…groups. Collaboration with @thetuningspoon for boot performance improvement on installations with large quantities of fields/templates/fieldgroups. Lazy loading option is enabled by default but can be disabled by setting $config->useLazyLoading=false; in your /site/config.php file.

Co-authored-by: thetuningspoon <mspooner@hey.com>

wire/config.php

@@ -12,7 +12,7 @@
  * You may also make up your own configuration options by assigning them 
  * in /site/config.php 
  * 
- * ProcessWire 3.x, Copyright 2016 by Ryan Cramer
+ * ProcessWire 3.x, Copyright 2022 by Ryan Cramer
  * https://processwire.com
  *
  * 
@@ -76,12 +76,15 @@
 /**
  * Tools, and their order, to show in debug mode (admin)
  * 
- * Options include: pages, api, session, modules, hooks, database, db, timers, user, input, cache, autoload
+ * Options include: pages, api, session, modules, hooks, database, db, timers, user, input, cache, autoload, lazyload
+ * 
+ * Note: when used, lazyload option should be placed first beause its results can be affected by later debug tools.
  * 
  * @var array
  * 
  */
 $config->debugTools = array(
+	//'lazyload',
 	'pages',
 	'api',
 	'session',
@@ -194,6 +197,23 @@
  */
 $config->usePageClasses = false;
 
+/**
+ * Use lazy loading of fields (plus templates and fieldgroups) for faster boot times?
+ * 
+ * This delays loading of fields, templates and fieldgroups until they are requested.
+ * This can improve performance on systems with hundreds of fields or templates, as 
+ * individual fields, templates/fieldgroups won't get constructed until they are needed.
+ * 
+ * Specify `true` to use lazy loading for all types, `false` to disable all lazy loading, 
+ * or specify array with one or more of the following for lazy loading only certain types:
+ * `[ 'fields', 'templates', 'fieldgroups' ]`
+ * 
+ * @var bool|array
+ * @since 3.0.194
+ * 
+ */
+$config->useLazyLoading = true;
+
 /**
  * Disable all HTTPS requirements?
  * 

wire/core/Config.php

@@ -148,6 +148,7 @@
  * @property bool $usePoweredBy Use the x-powered-by header? Set to false to disable. #pw-group-system
  * @property bool $useFunctionsAPI Allow most API variables to be accessed as functions? (see /wire/core/FunctionsAPI.php) #pw-group-system
  * @property bool $useMarkupRegions Enable support for front-end markup regions? #pw-group-system
+ * @property bool|array $useLazyLoading Delay loading of fields (and templates/fieldgroups) till requested? Can improve performance on systems with lots of fields or templates. #pw-group-system @since 3.0.193
  * @property bool $usePageClasses Use custom Page classes in `/site/classes/[TemplateName]Page.php`? #pw-group-system @since 3.0.152
  * @property int $lazyPageChunkSize Chunk size for for $pages->findMany() calls. #pw-group-system
  *