diff --git a/public/index.html b/public/index.html
index 77e5f14..6aacca4 100644
--- a/public/index.html
+++ b/public/index.html
@@ -33,6 +33,10 @@
         _czc.push(["_setCustomVar","has_token",localStorage['TOKEN']?'yes':'no',1]);
         _czc.push(["_setCustomVar","standalone",((window.matchMedia('(display-mode: standalone)').matches) || (window.navigator.standalone))?'yes':'no',1]);
         _czc.push(["_setCustomVar","build_info","%REACT_APP_BUILD_INFO%"||'---']);
+        var cr_version=/Chrome\/(\d+)/.exec(navigator.userAgent);
+        _czc.push(["_setCustomVar","cr_version_test",cr_version?cr_version[1]:'[null]',2]);
+        /*
+        // track config
         try {
             var config=JSON.parse(localStorage['hole_config']||'{}');
             for(var key in config)
@@ -42,6 +46,7 @@
         } catch(e) {
             console.trace(e);
         }
+        */
         var cnzz_s_tag = document.createElement('script');
         cnzz_s_tag.type = 'text/javascript';
         cnzz_s_tag.async = true;
diff --git a/src/Config.js b/src/Config.js
index fe851ea..cf5cb9f 100644
--- a/src/Config.js
+++ b/src/Config.js
@@ -14,9 +14,7 @@ const DEFAULT_CONFIG={
     background_img: 'static/bg/gbp.jpg',
     background_color: '#113366',
     pressure: false,
-    horizontal_scroll: true,
     easter_egg: true,
-    comment_cache: false,
     color_scheme: 'default',
 };
 
@@ -223,7 +221,6 @@ export class ConfigUI extends PureComponent {
             <div>
                 <div className="box config-ui-header">
                     <p>这些功能仍在测试，可能不稳定（<a onClick={this.reset_settings.bind(this)}>全部重置</a>）</p>
-                    <p>我们会收集你的设置，以用于改进产品</p>
                     <p><b>修改设置后 <a onClick={()=>{window.location.reload()}}>刷新页面</a> 方可生效</b></p>
                 </div>
                 <div className="box">
@@ -235,14 +232,6 @@ export class ConfigUI extends PureComponent {
                                   description="短暂按住 Esc 键或重压屏幕（3D Touch）可以快速返回或者刷新树洞"
                     />
                     <hr />
-                    <ConfigSwitch callback={this.save_changes_bound} id="horizontal_scroll" name="横向滚动"
-                                  description="在树洞列表里横向滚动浏览回复，如果经常误触可以把它关掉"
-                    />
-                    <hr />
-                    <ConfigSwitch callback={this.save_changes_bound} id="comment_cache" name="评论缓存"
-                                  description="缓存已读树洞的评论（加载更快，但可能有bug）"
-                    />
-                    <hr />
                     <ConfigSwitch callback={this.save_changes_bound} id="easter_egg" name="允许彩蛋"
                                   description="在某些情况下显示彩蛋"
                     />
diff --git a/src/Flows.css b/src/Flows.css
index c289c10..6875333 100644
--- a/src/Flows.css
+++ b/src/Flows.css
@@ -53,9 +53,6 @@
     padding-left: 18px;
     overflow-x: auto;
 }
-.flow-reply-row.config-no-scroll {
-    overflow-x: hidden !important;
-}
 
 .flow-reply-row::-webkit-scrollbar {
     display: none;
diff --git a/src/Flows.js b/src/Flows.js
index 8d39d2f..7609afa 100644
--- a/src/Flows.js
+++ b/src/Flows.js
@@ -532,7 +532,7 @@ class FlowItemRow extends PureComponent {
             }}>
                 <FlowItem parts={parts} info={this.state.info} attention={this.state.attention} img_clickable={false} is_quote={this.props.is_quote}
                     color_picker={this.color_picker} show_pid={show_pid} replies={this.state.replies} />
-                <div className={'flow-reply-row'+(window.config.horizontal_scroll ? '' : ' config-no-scroll')}>
+                <div className="flow-reply-row">
                     {this.state.reply_status==='loading' && <div className="box box-tip">加载中</div>}
                     {this.state.reply_status==='failed' &&
                         <div className="box box-tip"><a onClick={()=>{this.load_replies()}}>重新加载</a></div>
diff --git a/src/cache.js b/src/cache.js
index 44bbf61..c8debe7 100644
--- a/src/cache.js
+++ b/src/cache.js
@@ -6,23 +6,21 @@ class Cache {
     constructor() {
         this.db=null;
         this.added_items_since_maintenance=0;
-        if(window.config.comment_cache) {
-            const open_req=indexedDB.open('hole_cache_db',CACHE_DB_VER);
-            open_req.onerror=console.error.bind(console);
-            open_req.onupgradeneeded=(event)=>{
-                console.log('comment cache db upgrade');
-                const db=event.target.result;
-                const store=db.createObjectStore('comment',{
-                    keyPath: 'pid',
-                });
-                store.createIndex('last_access','last_access',{unique: false});
-            };
-            open_req.onsuccess=(event)=>{
-                console.log('comment cache db loaded');
-                this.db=event.target.result;
-                setTimeout(this.maintenance.bind(this),1);
-            };
-        }
+        const open_req=indexedDB.open('hole_cache_db',CACHE_DB_VER);
+        open_req.onerror=console.error.bind(console);
+        open_req.onupgradeneeded=(event)=>{
+            console.log('comment cache db upgrade');
+            const db=event.target.result;
+            const store=db.createObjectStore('comment',{
+                keyPath: 'pid',
+            });
+            store.createIndex('last_access','last_access',{unique: false});
+        };
+        open_req.onsuccess=(event)=>{
+            console.log('comment cache db loaded');
+            this.db=event.target.result;
+            setTimeout(this.maintenance.bind(this),1);
+        };
     }
 
     get(pid,target_version) {
@@ -35,15 +33,15 @@ class Cache {
             get_req.onsuccess=()=>{
                 let res=get_req.result;
                 if(!res)  {
-                    console.log('cache miss');
+                    //console.log('comment cache miss '+pid);
                     resolve(null);
                 } else if(target_version===res.version) { // hit
-                    console.log('cache hit');
+                    console.log('comment cache hit '+pid);
                     res.last_access=(+new Date());
                     store.put(res);
                     resolve(res.data);
                 } else { // expired
-                    console.log('cache expired: ver',res.version,'target',target_version);
+                    console.log('comment cache expired '+pid+': ver',res.version,'target',target_version);
                     store.delete(pid);
                     resolve(null);
                 }