diff --git a/abstract/Block.js b/abstract/Block.js
index 1546c8a5c..442fe28a2 100644
--- a/abstract/Block.js
+++ b/abstract/Block.js
@@ -174,6 +174,7 @@ export class Block extends BaseComponent {
     if (!this.has('*eventEmitter')) {
       this.add('*eventEmitter', new EventEmitter(this.debugPrint.bind(this)));
     }
+
     if (!this.has('*localeManager')) {
       this.add('*localeManager', new LocaleManager(this));
     }
@@ -276,9 +277,6 @@ export class Block extends BaseComponent {
             return false;
           }
           const sharedKey = sharedConfigKey(/** @type {keyof import('../types').ConfigType} */ (key));
-          if (!this.has(sharedKey)) {
-            this.add(sharedKey, initialConfig[/** @type {keyof import('../types').ConfigType} */ (key)]);
-          }
           this.$[sharedKey] = value;
           return true;
         },
@@ -287,10 +285,6 @@ export class Block extends BaseComponent {
          * @param {keyof import('../types').ConfigType} key
          */
         get: (obj, key) => {
-          const sharedKey = sharedConfigKey(key);
-          if (!this.has(sharedKey)) {
-            this.add(sharedKey, initialConfig[key]);
-          }
           return this.$[sharedConfigKey(key)];
         },
       });
@@ -304,11 +298,7 @@ export class Block extends BaseComponent {
    * @param {(value: import('../types').ConfigType[T]) => void} callback
    */
   subConfigValue(key, callback) {
-    const sharedKey = sharedConfigKey(key);
-    if (!this.has(sharedKey)) {
-      this.add(sharedKey, initialConfig[key]);
-    }
-    this.sub(sharedKey, callback);
+    this.sub(sharedConfigKey(key), callback);
   }
 
   /** @param {unknown[]} args */
diff --git a/blocks/FileItem/FileItem.js b/blocks/FileItem/FileItem.js
index d9ca7ad3c..5680f7eaa 100644
--- a/blocks/FileItem/FileItem.js
+++ b/blocks/FileItem/FileItem.js
@@ -150,18 +150,8 @@ export class FileItem extends UploaderBlock {
       return;
     }
 
-    if (entry.getValue('file')?.type.includes('image')) {
-      try {
-        let thumbUrl = await generateThumb(entry.getValue('file'), this.cfg.thumbSize);
-        entry.setValue('thumbUrl', thumbUrl);
-      } catch (err) {
-        let color = window.getComputedStyle(this).getPropertyValue('--clr-generic-file-icon');
-        entry.setValue('thumbUrl', fileCssBg(color));
-      }
-    } else {
-      let color = window.getComputedStyle(this).getPropertyValue('--clr-generic-file-icon');
-      entry.setValue('thumbUrl', fileCssBg(color));
-    }
+    let color = window.getComputedStyle(this).getPropertyValue('--clr-generic-file-icon');
+    entry.setValue('thumbUrl', fileCssBg(color));
   }
 
   /**
@@ -310,8 +300,6 @@ export class FileItem extends UploaderBlock {
 
     /** @private */
     this._observer = new window.IntersectionObserver(this._observerCallback.bind(this), {
-      root: this.parentElement,
-      rootMargin: '50% 0px 50% 0px',
       threshold: [0, 1],
     });
     this._observer.observe(this);
diff --git a/blocks/FileItem/file-item.css b/blocks/FileItem/file-item.css
index 30c2157d8..ab03deab6 100644
--- a/blocks/FileItem/file-item.css
+++ b/blocks/FileItem/file-item.css
@@ -1,6 +1,17 @@
 lr-file-item {
   display: block;
+  content-visibility: auto;
+
+  /* TODO: extract to theme */
+  height: 56px;
+  contain-intrinsic-size: auto 56px;
+}
+
+lr-file-item:last-of-type {
+  height: 52px;
+  contain-intrinsic-size: auto 52px;
 }
+
 lr-file-item > .inner {
   position: relative;
   display: grid;
@@ -13,7 +24,6 @@ lr-file-item > .inner {
   font-size: 0.95em;
   background-color: var(--clr-background);
   border-radius: var(--border-radius-element);
-  transition: var(--transition-duration);
 }
 
 lr-file-item:last-of-type > .inner {
@@ -53,7 +63,6 @@ lr-file-item .file-name-wrapper {
   padding-left: var(--gap-mid);
   overflow: hidden;
   color: var(--clr-txt-light);
-  transition: color var(--transition-duration);
 }
 
 lr-file-item .file-name {
@@ -94,7 +103,6 @@ lr-file-item .badge {
   border-radius: 50%;
   transform: scale(0.3);
   opacity: 0;
-  transition: var(--transition-duration) ease;
   display: flex;
   justify-content: center;
   align-items: center;