fix: Add a 0.1 second delay between redrawing Tasks search results.

Basically, many Tasks searches can take more than 0.1 second to render.
But Obsidian and Tasks can parse many files during that 0.1 second span.

1. This speeds up start-up time in cases where there were Tasks queries open
   at start-up Obsidian, preventing double-redraws.
2. It eliminates lots of wasted redraws in open queries, when Obsidian
   is re-reading files that were edited externally (such as via Sync)
   and where bulk edits are made to files in the vault.

Relates to issue #3283

Author: claremacrae

src/Obsidian/Cache.ts

@@ -1,4 +1,12 @@
-import type { CachedMetadata, EventRef, HeadingCache, ListItemCache, SectionCache, Workspace } from 'obsidian';
+import {
+    type CachedMetadata,
+    type EventRef,
+    type HeadingCache,
+    type ListItemCache,
+    type SectionCache,
+    type Workspace,
+    debounce,
+} from 'obsidian';
 import { MetadataCache, Notice, TAbstractFile, TFile, Vault } from 'obsidian';
 import { Mutex } from 'async-mutex';
 import { TasksFile } from '../Scripting/TasksFile';
@@ -33,6 +41,12 @@ export class Cache {
     private state: State;
     private tasks: Task[];
 
+    private readonly notifySubscribersDebounced = debounce(
+        () => this.notifySubscribersNotDebounced(),
+        100, // Long enough to prevent successive redraws slowing performance; short enough for edits via context menus to appear snappy
+        true,
+    );
+
     /**
      * We cannot know if this class will be instantiated because obsidian started
      * or because the plugin was activated later. This means we have to load the
@@ -111,7 +125,7 @@ export class Cache {
 
     private notifySubscribers(): void {
         this.logger.debug('Cache.notifySubscribers()');
-        this.notifySubscribersNotDebounced();
+        this.notifySubscribersDebounced();
     }
 
     private notifySubscribersNotDebounced(): void {