diff --git a/src/misc/wasm/package.py b/src/misc/wasm/package.py
--- a/src/misc/wasm/package.py
+++ b/src/misc/wasm/package.py
@@ -48,6 +48,6 @@
 BOOT_GROUPS = ['progs/', 'styles/', 'packages/', 'texts/', 'plugins/', 'cache/',
                'langs/encoding/', 'fonts/tfm/', 'fonts/enc/', 'fonts/virtual/',
-               'misc/pixmaps/neoclassical/light/']
+               'misc/pixmaps/neoclassical/light/', 'misc/pixmaps/lucide/']
 BOOT_FILES = ['fonts/font-database.scm', 'fonts/font-characteristics.scm',
               'fonts/font-features.scm', 'fonts/font-substitutions.scm',
               'fonts/pdf-font-issues.scm',
diff --git a/src/misc/wasm/web-pre.js b/src/misc/wasm/web-pre.js
--- a/src/misc/wasm/web-pre.js
+++ b/src/misc/wasm/web-pre.js
@@ -174,4 +174,14 @@
     ENV['TEXMACS_TESSERA_EDITOR'] = '1';
     FS.mkdirTree ('/home/web/.TeXmacs');
+    // Keep the compiled font and file cache between editor iframes without
+    // persisting the embedded editor's preferences or working documents.
+    var cachePath = '/home/web/.TeXmacs/system/cache';
+    FS.mkdirTree (cachePath);
+    FS.mount (IDBFS, { autoPersist: true }, cachePath);
+    addRunDependency ('tm-embedded-font-cache');
+    FS.syncfs (true, function (err) {
+      if (err) console.error ('TeXmacs: cannot read the saved font cache', err);
+      removeRunDependency ('tm-embedded-font-cache');
+    });
     return;
   }
*** End Patch