diff --git a/app/build.gradle b/app/build.gradle
index 4d3d546e..f9067e23 100644
--- a/app/build.gradle
+++ b/app/build.gradle
@@ -38,7 +38,7 @@ android {
         minSdkVersion 16
         targetSdkVersion 30
         versionCode 61
-        versionName "5.1.2"
+        versionName "5.1.2-alpha1"
         testInstrumentationRunner "androidx.test.runner.AndroidJUnitRunner"
         vectorDrawables.useSupportLibrary = true
     }
@@ -90,6 +90,7 @@ dependencies {
     implementation "androidx.constraintlayout:constraintlayout:2.0.1"
     implementation "androidx.gridlayout:gridlayout:1.0.0"
     implementation "androidx.biometric:biometric:1.0.1"
+    implementation "androidx.work:work-runtime-ktx:2.4.0"
 
     implementation "com.daimajia.swipelayout:library:1.2.0@aar"
 
@@ -125,7 +126,7 @@ dependencies {
     implementation "ru.noties.markwon:core:3.1.0"
 
     implementation "xyz.quaver:libpupil:1.7.2"
-    implementation "xyz.quaver:documentfilex:0.2.15"
+    implementation "xyz.quaver:documentfilex:0.3"
     implementation "xyz.quaver:floatingsearchview:1.0.7"
 
     testImplementation "junit:junit:4.13"
diff --git a/app/release/output-metadata.json b/app/release/output-metadata.json
index 5557886d..d1f76a9e 100644
--- a/app/release/output-metadata.json
+++ b/app/release/output-metadata.json
@@ -12,7 +12,7 @@
       "filters": [],
       "properties": [],
       "versionCode": 61,
-      "versionName": "5.1.1-hotfix3",
+      "versionName": "5.1.2-alpha1",
       "enabled": true,
       "outputFile": "app-release.apk"
     }
diff --git a/app/src/main/java/xyz/quaver/pupil/adapters/GalleryBlockAdapter.kt b/app/src/main/java/xyz/quaver/pupil/adapters/GalleryBlockAdapter.kt
index 28f31f11..47bbe696 100644
--- a/app/src/main/java/xyz/quaver/pupil/adapters/GalleryBlockAdapter.kt
+++ b/app/src/main/java/xyz/quaver/pupil/adapters/GalleryBlockAdapter.kt
@@ -61,9 +61,18 @@ class GalleryBlockAdapter(private val galleries: List<Int>) : RecyclerSwipeAdapt
     var thin: Boolean = Preferences["thin"]
 
     inner class GalleryViewHolder(val view: View) : RecyclerView.ViewHolder(view) {
-        var update = true
+        private var galleryID: Int = 0
 
-        private fun updateProgress(context: Context, galleryID: Int) {
+        init {
+            CoroutineScope(Dispatchers.Main).launch {
+                while (updateAll) {
+                    updateProgress(view.context)
+                    delay(1000)
+                }
+            }
+        }
+
+        private fun updateProgress(context: Context) {
             val cache = Cache.getInstance(context, galleryID)
 
             CoroutineScope(Dispatchers.Main).launch {
@@ -116,9 +125,13 @@ class GalleryBlockAdapter(private val galleries: List<Int>) : RecyclerSwipeAdapt
         }
 
         fun bind(galleryID: Int) {
+            this.galleryID = galleryID
+
             val cache = Cache.getInstance(view.context, galleryID)
 
-            val galleryBlock = cache.metadata.galleryBlock ?: return
+            val galleryBlock = runBlocking {
+                cache.getGalleryBlock()
+            } ?: return
 
             with(view) {
                 val resources = context.resources
@@ -162,13 +175,6 @@ class GalleryBlockAdapter(private val galleries: List<Int>) : RecyclerSwipeAdapt
                     }
                 }
 
-                CoroutineScope(Dispatchers.Main).launch {
-                    while (updateAll && update) {
-                        updateProgress(context, galleryID)
-                        delay(1000)
-                    }
-                }
-
                 galleryblock_title.text = galleryBlock.title
                 with(galleryblock_artist) {
                     text = artists.joinToString { it.wordCapitalize() }
@@ -377,13 +383,6 @@ class GalleryBlockAdapter(private val galleries: List<Int>) : RecyclerSwipeAdapt
         }
     }
 
-    override fun onViewDetachedFromWindow(holder: RecyclerView.ViewHolder) {
-        super.onViewDetachedFromWindow(holder)
-
-        if (holder is GalleryViewHolder)
-            holder.update = false
-    }
-
     override fun getItemCount() =
         galleries.size +
         (if (showNext) 1 else 0) +
diff --git a/app/src/main/java/xyz/quaver/pupil/adapters/ReaderAdapter.kt b/app/src/main/java/xyz/quaver/pupil/adapters/ReaderAdapter.kt
index f62199d1..ce47fb60 100644
--- a/app/src/main/java/xyz/quaver/pupil/adapters/ReaderAdapter.kt
+++ b/app/src/main/java/xyz/quaver/pupil/adapters/ReaderAdapter.kt
@@ -62,7 +62,14 @@ class ReaderAdapter(
 
     class ViewHolder(val view: View) : RecyclerView.ViewHolder(view) {
         fun clear() {
-            view.image.ssiv?.recycle()
+            view.image.mainView.let {
+                when (it) {
+                    is SubsamplingScaleImageView ->
+                        it.recycle()
+                    is SimpleDraweeView ->
+                        it.controller = null
+                }
+            }
         }
     }
 
diff --git a/app/src/main/java/xyz/quaver/pupil/services/DownloadService.kt b/app/src/main/java/xyz/quaver/pupil/services/DownloadService.kt
index 1fcacd4f..f6bc889f 100644
--- a/app/src/main/java/xyz/quaver/pupil/services/DownloadService.kt
+++ b/app/src/main/java/xyz/quaver/pupil/services/DownloadService.kt
@@ -42,6 +42,7 @@ import xyz.quaver.pupil.R
 import xyz.quaver.pupil.client
 import xyz.quaver.pupil.interceptors
 import xyz.quaver.pupil.ui.ReaderActivity
+import xyz.quaver.pupil.util.cleanCache
 import xyz.quaver.pupil.util.downloader.Cache
 import xyz.quaver.pupil.util.downloader.DownloadManager
 import xyz.quaver.pupil.util.ellipsize
@@ -295,6 +296,8 @@ class DownloadService : Service() {
     }
 
     fun download(galleryID: Int, priority: Boolean = false, startId: Int? = null): Job = CoroutineScope(Dispatchers.IO).launch {
+        cleanCache(this@DownloadService)
+
         if (progress.containsKey(galleryID))
             cancel(galleryID)
 
diff --git a/app/src/main/java/xyz/quaver/pupil/ui/fragment/ManageStorageFragment.kt b/app/src/main/java/xyz/quaver/pupil/ui/fragment/ManageStorageFragment.kt
index 9afdb6eb..628a7f9b 100644
--- a/app/src/main/java/xyz/quaver/pupil/ui/fragment/ManageStorageFragment.kt
+++ b/app/src/main/java/xyz/quaver/pupil/ui/fragment/ManageStorageFragment.kt
@@ -31,6 +31,7 @@ import xyz.quaver.io.util.deleteRecursively
 import xyz.quaver.pupil.R
 import xyz.quaver.pupil.histories
 import xyz.quaver.pupil.util.byteToString
+import xyz.quaver.pupil.util.downloader.Cache
 import xyz.quaver.pupil.util.downloader.DownloadManager
 import java.io.File
 
@@ -61,6 +62,8 @@ class ManageStorageFragment : PreferenceFragmentCompat(), Preference.OnPreferenc
                             if (dir.exists())
                                 dir.deleteRecursively()
 
+                            Cache.instances.clear()
+
                             summary = context.getString(R.string.settings_storage_usage, byteToString(0))
                             CoroutineScope(Dispatchers.IO).launch {
                                 var size = 0L
diff --git a/app/src/main/java/xyz/quaver/pupil/util/downloader/Cache.kt b/app/src/main/java/xyz/quaver/pupil/util/downloader/Cache.kt
index dacd54ad..5c4aa5f1 100644
--- a/app/src/main/java/xyz/quaver/pupil/util/downloader/Cache.kt
+++ b/app/src/main/java/xyz/quaver/pupil/util/downloader/Cache.kt
@@ -186,7 +186,7 @@ class Cache private constructor(context: Context, val galleryID: Int) : ContextW
     }
 
     fun getImage(index: Int): FileX? =
-        metadata.imageList?.get(index)?.let { findFile(it) }
+        metadata.imageList?.getOrNull(index)?.let { findFile(it) }
 
     @Suppress("BlockingMethodInNonBlockingContext")
     fun putImage(index: Int, fileName: String, data: ByteArray) {
diff --git a/app/src/main/java/xyz/quaver/pupil/util/file.kt b/app/src/main/java/xyz/quaver/pupil/util/file.kt
index 7579f986..2df6e90e 100644
--- a/app/src/main/java/xyz/quaver/pupil/util/file.kt
+++ b/app/src/main/java/xyz/quaver/pupil/util/file.kt
@@ -19,35 +19,63 @@
 package xyz.quaver.pupil.util
 
 import android.content.Context
-import android.os.storage.StorageManager
-import androidx.core.content.ContextCompat
-import androidx.core.net.toUri
+import kotlinx.coroutines.CoroutineScope
+import kotlinx.coroutines.Dispatchers
+import kotlinx.coroutines.launch
+import kotlinx.coroutines.sync.Mutex
+import kotlinx.coroutines.sync.withLock
+import xyz.quaver.pupil.histories
+import xyz.quaver.pupil.util.downloader.Cache
+import xyz.quaver.pupil.util.downloader.DownloadManager
 import java.io.File
-import java.io.FileOutputStream
-import java.lang.reflect.Array
-import java.net.URL
-
-@Suppress("DEPRECATION")
-@Deprecated("Use downloader.Cache instead")
-fun getCachedGallery(context: Context, galleryID: Int) =
-    File(getDownloadDirectory(context), galleryID.toString()).let {
-        if (it.exists())
-            it
-        else
-            File(context.cacheDir, "imageCache/$galleryID")
-    }
 
-@Suppress("DEPRECATION")
-@Deprecated("Use downloader.Cache instead")
-fun getDownloadDirectory(context: Context) =
-    Preferences.get<String>("dl_location").let {
-        if (it.isNotEmpty() && !it.startsWith("content"))
-            File(it)
-        else
-            context.getExternalFilesDir(null)!!
-    }
+val mutex = Mutex()
+fun cleanCache(context: Context) = CoroutineScope(Dispatchers.IO).launch {
+    if (mutex.isLocked) return@launch
+
+    mutex.withLock {
+        val cacheFolder = File(context.cacheDir, "imageCache")
+        val downloadManager = DownloadManager.getInstance(context)
+
+        cacheFolder.listFiles { file ->
+            val galleryID = file.name.toIntOrNull() ?: return@listFiles true
+
+            !(downloadManager.downloadFolderMap.containsKey(galleryID) || histories.contains(galleryID))
+        }?.forEach {
+            it.deleteRecursively()
+        }
+
+        DownloadManager.getInstance(context).downloadFolderMap.keys.forEach {
+            val folder = File(cacheFolder, it.toString())
+
+            if (!downloadManager.isDownloading(it) && folder.exists()) {
+                folder.deleteRecursively()
+            }
+        }
 
-@Suppress("DEPRECATION")
-@Deprecated("Use FileX instead")
-fun File.isParentOf(another: File) =
-    another.absolutePath.startsWith(this.absolutePath)
\ No newline at end of file
+        val limit = (Preferences.get<String>("cache_limit").toLongOrNull() ?: 0L)*1024*1024*1024
+
+        if (limit == 0L) return@withLock
+
+        val cacheSize = {
+            var size = 0L
+
+            cacheFolder.walk().forEach {
+                size += it.length()
+            }
+
+            size
+        }
+
+        if (cacheSize.invoke() > limit)
+            while (cacheSize.invoke() > limit/2) {
+                val caches = cacheFolder.list() ?: return@withLock
+
+                (histories.firstOrNull {
+                    caches.contains(it.toString()) && !downloadManager.isDownloading(it)
+                } ?: return@withLock).let {
+                    Cache.delete(it)
+                }
+            }
+    }
+}
\ No newline at end of file
diff --git a/app/src/main/res/values-ja/strings.xml b/app/src/main/res/values-ja/strings.xml
index b814256d..ac6869c1 100644
--- a/app/src/main/res/values-ja/strings.xml
+++ b/app/src/main/res/values-ja/strings.xml
@@ -150,4 +150,6 @@
     <string name="camera_denied">カメラ権限が拒否されているため、まばたき検知使用できません</string>
     <string name="no_camera">この機器には前面カメラが装着されていません</string>
     <string name="error">エラー</string>
+    <string name="settings_cache_limit">キャッシュサイズ制限</string>
+    <string name="settings_cache_unlimited">制限なし</string>
 </resources>
\ No newline at end of file
diff --git a/app/src/main/res/values-ko/strings.xml b/app/src/main/res/values-ko/strings.xml
index c1ac6072..58979aec 100644
--- a/app/src/main/res/values-ko/strings.xml
+++ b/app/src/main/res/values-ko/strings.xml
@@ -150,4 +150,6 @@
     <string name="camera_denied">카메라 권한이 거부되었기 때문에 눈 깜빡임 감지가 불가능합니다</string>
     <string name="no_camera">이 장치에는 전면 카메라가 없습니다</string>
     <string name="error">오류</string>
+    <string name="settings_cache_limit">캐시 크기 제한</string>
+    <string name="settings_cache_unlimited">무제한</string>
 </resources>
\ No newline at end of file
diff --git a/app/src/main/res/values/arrays.xml b/app/src/main/res/values/arrays.xml
index 8e9b419a..69abcd7e 100644
--- a/app/src/main/res/values/arrays.xml
+++ b/app/src/main/res/values/arrays.xml
@@ -58,4 +58,24 @@
         <item>SOCKS</item>
     </string-array>
 
+    <string-array name="cache_size">
+        <item>0</item>
+        <item>1</item>
+        <item>2</item>
+        <item>4</item>
+        <item>8</item>
+        <item>16</item>
+        <item>32</item>
+    </string-array>
+
+    <string-array name="cache_size_text">
+        <item>@string/settings_cache_unlimited</item>
+        <item>1G</item>
+        <item>2G</item>
+        <item>4G</item>
+        <item>8G</item>
+        <item>16G</item>
+        <item>32G</item>
+    </string-array>
+
 </resources>
\ No newline at end of file
diff --git a/app/src/main/res/values/strings.xml b/app/src/main/res/values/strings.xml
index 5248858b..53d185b4 100644
--- a/app/src/main/res/values/strings.xml
+++ b/app/src/main/res/values/strings.xml
@@ -161,6 +161,9 @@
     <string name="settings_download_folder_available">%s available</string>
     <string name="settings_download_folder_custom">Custom Location</string>
     <string name="settings_download_folder_not_writable">This folder is not writable. Please select another folder.</string>
+    <string name="settings_cache_limit">Cache Limit</string>
+    <string name="settings_cache_unlimited">Unlimited</string>
+    <string name="settings_nomedia_title">Hide image from gallery</string>
     <string name="settings_low_quality">Low quality images</string>
     <string name="settings_low_quality_summary">Load low quality images to improve load speed and data usage</string>
 
@@ -179,7 +182,6 @@
     <string name="settings_security_mode_summary">Enable security mode to make the screen invisible on recent app window</string>
     <string name="settings_dark_mode_title">Dark mode</string>
     <string name="settings_dark_mode_summary">Protect yourself against light attacks!</string>
-    <string name="settings_nomedia_title">Hide image from gallery</string>
     <string name="settings_import_old_galleries">Import old galleries</string>
     <string name="settings_user_id">User ID</string>
     <string name="settings_user_id_toast">User ID is copied to clipboard</string>
diff --git a/app/src/main/res/xml/root_preferences.xml b/app/src/main/res/xml/root_preferences.xml
index 7a5e9cba..ff67535d 100644
--- a/app/src/main/res/xml/root_preferences.xml
+++ b/app/src/main/res/xml/root_preferences.xml
@@ -44,6 +44,14 @@
             app:key="download_folder"
             app:title="@string/settings_download_folder"/>
 
+        <ListPreference
+            app:key="cache_limit"
+            app:title="@string/settings_cache_limit"
+            app:entries="@array/cache_size_text"
+            app:entryValues="@array/cache_size"
+            app:defaultValue="8"
+            app:useSimpleSummaryProvider="true"/>
+
         <SwitchPreferenceCompat
             app:key="nomedia"
             app:title="@string/settings_nomedia_title"/>