diff --git a/app/build.gradle b/app/build.gradle
index 2fa0434..7097a60 100644
--- a/app/build.gradle
+++ b/app/build.gradle
@@ -45,6 +45,8 @@ android {
 dependencies {
     implementation fileTree(include: ['*.jar'], dir: 'libs')
     implementation "org.jetbrains.kotlin:kotlin-stdlib-jre7:$kotlin_version"
+    implementation "org.jetbrains.kotlinx:kotlinx-coroutines-core:$coroutines_version"
+    implementation "org.jetbrains.kotlinx:kotlinx-coroutines-android:$coroutines_version"
     implementation "com.android.support:recyclerview-v7:$android_version"
     implementation "com.android.support:appcompat-v7:$android_version"
     implementation "com.android.support:design:$android_version"
@@ -61,5 +63,11 @@ dependencies {
     androidTestImplementation 'com.android.support.test.espresso:espresso-core:3.0.1'
 }
 
+kotlin {
+    experimental {
+        coroutines "enable"
+    }
+}
+
 
 
diff --git a/app/src/androidTest/java/org/mixitconf/repository/EventReaderTest.kt b/app/src/androidTest/java/org/mixitconf/repository/EventReaderTest.kt
index 0c853b5..4972be8 100644
--- a/app/src/androidTest/java/org/mixitconf/repository/EventReaderTest.kt
+++ b/app/src/androidTest/java/org/mixitconf/repository/EventReaderTest.kt
@@ -20,7 +20,7 @@ class EventReaderTest {
     @Before
     fun init() {
         appContext = InstrumentationRegistry.getTargetContext()
-        reader = EventReader(appContext)
+        reader = EventReader.getInstance(appContext)
     }
 
     @Test
diff --git a/app/src/androidTest/java/org/mixitconf/repository/TalkReaderTest.kt b/app/src/androidTest/java/org/mixitconf/repository/TalkReaderTest.kt
index dedd54c..f7f994b 100644
--- a/app/src/androidTest/java/org/mixitconf/repository/TalkReaderTest.kt
+++ b/app/src/androidTest/java/org/mixitconf/repository/TalkReaderTest.kt
@@ -21,7 +21,7 @@ class TalkReaderTest {
     @Before
     fun init() {
         appContext = InstrumentationRegistry.getTargetContext()
-        reader = TalkReader(appContext)
+        reader = TalkReader.getInstance(appContext)
     }
 
     @Test
diff --git a/app/src/androidTest/java/org/mixitconf/repository/UserReaderTest.kt b/app/src/androidTest/java/org/mixitconf/repository/UserReaderTest.kt
index 695554f..48713df 100644
--- a/app/src/androidTest/java/org/mixitconf/repository/UserReaderTest.kt
+++ b/app/src/androidTest/java/org/mixitconf/repository/UserReaderTest.kt
@@ -19,7 +19,7 @@ class UserReaderTest {
     @Before
     fun init() {
         appContext = InstrumentationRegistry.getTargetContext()
-        reader = UserReader(appContext)
+        reader = UserReader.getInstance(appContext)
     }
 
     @Test
diff --git a/app/src/main/java/org/mixitconf/MainActivity.kt b/app/src/main/java/org/mixitconf/MainActivity.kt
index 0c5d22e..b866492 100644
--- a/app/src/main/java/org/mixitconf/MainActivity.kt
+++ b/app/src/main/java/org/mixitconf/MainActivity.kt
@@ -5,10 +5,14 @@ import android.net.Uri
 import android.os.Bundle
 import android.support.design.widget.BottomNavigationView
 import android.support.v7.app.AppCompatActivity
+import android.util.Log
 import android.view.Menu
 import android.view.MenuItem
 import kotlinx.android.synthetic.main.activity_main.*
+import kotlinx.coroutines.experimental.launch
 import org.mixitconf.fragment.*
+import org.mixitconf.repository.TalkReader
+import org.mixitconf.repository.UserReader
 import org.mixitconf.service.hasIntentPackage
 import org.mixitconf.service.openFragment
 import org.mixitconf.service.openFragmentDetail
@@ -20,6 +24,7 @@ open class MainActivity : AppCompatActivity(),
 
     override fun onCreate(savedInstanceState: Bundle?) {
         super.onCreate(savedInstanceState)
+        Log.i("MainActivity","onCreate start")
         setContentView(R.layout.activity_main)
 
         // Initialize the top action bar to display Home button
@@ -29,6 +34,11 @@ open class MainActivity : AppCompatActivity(),
         }
 
         navigation.setOnNavigationItemSelectedListener(onNavigationItemSelectedListener)
+
+        launch {
+            TalkReader.getInstance(baseContext)
+            UserReader.getInstance(baseContext)
+        }
     }
 
     /**
diff --git a/app/src/main/java/org/mixitconf/repository/EventReader.kt b/app/src/main/java/org/mixitconf/repository/EventReader.kt
index 316a2e9..0b17f26 100644
--- a/app/src/main/java/org/mixitconf/repository/EventReader.kt
+++ b/app/src/main/java/org/mixitconf/repository/EventReader.kt
@@ -11,18 +11,14 @@ import org.mixitconf.service.SingletonHolder
 /**
  * Events are read from Json file
  */
-class EventReader(val context: Context) {
+class EventReader(val events: List<Event>) {
 
-    private val objectMapper: ObjectMapper = jacksonObjectMapper()
+    fun findAll(): List<Event> = events
+    fun findOne(id: String): Event = events.first { it.id == id }
 
-    private fun readFile(): List<Event>{
-        val jsonInputStream = context.resources.openRawResource(R.raw.events)
-        return objectMapper.readValue(jsonInputStream)
-    }
-
-    fun findAll(): List<Event> = readFile()
-
-    fun findOne(id: String): Event = readFile().first { it.id == id }
-
-    companion object : SingletonHolder<EventReader, Context>(::EventReader)
+    companion object : SingletonHolder<EventReader, Context>({
+            val jsonInputStream = it.resources.openRawResource(R.raw.events)
+            val events:List<Event> =  jacksonObjectMapper().readValue(jsonInputStream)
+            EventReader(events)
+    })
 }
\ No newline at end of file
diff --git a/app/src/main/java/org/mixitconf/repository/TalkReader.kt b/app/src/main/java/org/mixitconf/repository/TalkReader.kt
index 007fcde..56344df 100644
--- a/app/src/main/java/org/mixitconf/repository/TalkReader.kt
+++ b/app/src/main/java/org/mixitconf/repository/TalkReader.kt
@@ -18,27 +18,17 @@ import java.util.*
 /**
  * Talk are read adjust Json file
  */
-class TalkReader(private val context: Context) {
+class TalkReader(val talks: List<Talk>, private val context: Context) {
 
-    private val objectMapper: ObjectMapper = jacksonObjectMapper()
+    companion object : SingletonHolder<TalkReader, Context>({
+        val jsonInputStream = it.resources.openRawResource(R.raw.talks_2018)
+        val talks:List<Talk> = jacksonObjectMapper().readValue(jsonInputStream)
+        TalkReader(talks, it)
+    })
 
-    companion object : SingletonHolder<TalkReader, Context>(::TalkReader) {
-        private val talks: MutableList<Talk> = mutableListOf()
-    }
+    fun findAll(): List<Talk> = talks
 
-    private fun readFile(): List<Talk> {
-        val jsonInputStream = context.resources.openRawResource(R.raw.talks_2018)
-        if (TalkReader.talks.isEmpty()) {
-            val talks: List<Talk> = objectMapper.readValue(jsonInputStream)
-            talks.forEach { TalkReader.talks.add(transformDate(it)) }
-        }
-        return TalkReader.talks
-
-    }
-
-    fun findAll(): List<Talk> = readFile()
-
-    fun findOne(id: String): Talk = readFile().first { it.id == id }
+    fun findOne(id: String): Talk = talks.first { it.id == id }
 
     fun findMarkers(): List<Talk> = listOf(
             createNonTalkMomentFirstDay(TalkFormat.DAY, 8, 0, R.string.event_day1),
diff --git a/app/src/main/java/org/mixitconf/repository/UserReader.kt b/app/src/main/java/org/mixitconf/repository/UserReader.kt
index 1c1d165..a30a620 100644
--- a/app/src/main/java/org/mixitconf/repository/UserReader.kt
+++ b/app/src/main/java/org/mixitconf/repository/UserReader.kt
@@ -11,26 +11,17 @@ import org.mixitconf.service.SingletonHolder
 /**
  * Speakers are read from Json file
  */
-class UserReader(private val context: Context) {
+class UserReader(val users: List<User>) {
 
-    private val objectMapper: ObjectMapper = jacksonObjectMapper()
+    fun findAll(): List<User> = users
 
-    private fun readFile(): List<User>{
-        val jsonInputStream = context.resources.openRawResource(R.raw.users)
-        if(UserReader.users.isEmpty()){
-            val users: List<User> = objectMapper.readValue(jsonInputStream)
-            users.forEach { UserReader.users.add(it) }
-        }
-        return UserReader.users
-    }
+    fun findOne(login: String): User = users.first { it.login == login }
 
-    fun findAll(): List<User> = readFile()
+    fun findByLogins(logins: List<String>): List<User> = users.filter { logins.contains(it.login) }
 
-    fun findOne(login: String): User = readFile().first { it.login == login }
-
-    fun findByLogins(logins: List<String>): List<User> = readFile().filter { logins.contains(it.login) }
-
-    companion object : SingletonHolder<UserReader, Context>(::UserReader){
-        private val users:MutableList<User> = mutableListOf()
-    }
+    companion object : SingletonHolder<UserReader, Context>({
+        val json = it.resources.openRawResource(R.raw.users)
+        val users : List<User> = jacksonObjectMapper().readValue(json)
+        UserReader(users)
+    })
 }
\ No newline at end of file
diff --git a/build.gradle b/build.gradle
index 37dfdb3..217c83b 100644
--- a/build.gradle
+++ b/build.gradle
@@ -2,6 +2,7 @@
 
 buildscript {
     ext.kotlin_version = '1.2.30'
+    ext.coroutines_version = '0.22.5'
     ext.android_version = '27.0.2'
     ext.jackson_version = '2.9.4'
     ext.txtmark_version = '0.13'