diff --git a/src/async_client.rs b/src/async_client.rs
index 090fa8f5..8c3a4808 100644
--- a/src/async_client.rs
+++ b/src/async_client.rs
@@ -29,7 +29,6 @@ use reqwest::header::{HeaderValue, InvalidHeaderValue};
 use url::Url;
 
 use ruma_api::{Endpoint, Outgoing};
-use ruma_client_api::Error as RumaClientError;
 use ruma_events::collections::all::RoomEvent;
 use ruma_events::room::message::MessageEventContent;
 use ruma_events::EventResult;
@@ -404,13 +403,19 @@ impl AsyncClient {
                         .await
                 };
 
-                let event = match decrypted_event {
-                    Some(e) => Arc::new(e.clone()),
-                    None => Arc::new(event.clone()),
-                };
+                if let Some(e) = decrypted_event {
+                    *event = e;
+                }
 
                 let callbacks = {
                     let mut cb_futures = self.event_callbacks.lock().unwrap();
+
+                    let event = if !cb_futures.is_empty() {
+                        Arc::new(event.clone())
+                    } else {
+                        continue;
+                    };
+
                     let mut callbacks = Vec::new();
 
                     for cb in &mut cb_futures.iter_mut() {
diff --git a/src/crypto/machine.rs b/src/crypto/machine.rs
index 917f8795..d4e3a2af 100644
--- a/src/crypto/machine.rs
+++ b/src/crypto/machine.rs
@@ -20,8 +20,8 @@ use std::result::Result as StdResult;
 use std::sync::Arc;
 
 use super::error::{OlmError, Result, SignatureError, VerificationResult};
-use super::memory_stores::GroupSessionStore;
-use super::olm::{Account, InboundGroupSession};
+use super::memory_stores::{GroupSessionStore, SessionStore};
+use super::olm::{Account, InboundGroupSession, Session};
 #[cfg(feature = "sqlite-cryptostore")]
 use super::store::sqlite::SqliteStore;
 use super::store::MemoryStore;
@@ -69,7 +69,9 @@ pub struct OlmMachine {
     /// Store for the encryption keys.
     /// Persists all the encrytpion keys so a client can resume the session
     /// without the need to create new keys.
-    store: Box<dyn CryptoStore>,
+    // store: Box<dyn CryptoStore>,
+    /// A cache of all the Olm sessions we know about.
+    sessions: SessionStore,
     /// A cache of all the inbound group sessions we know about.
     inbound_group_sessions: GroupSessionStore,
 }
@@ -87,7 +89,8 @@ impl OlmMachine {
             device_id: device_id.to_owned(),
             account: Arc::new(Mutex::new(Account::new())),
             uploaded_signed_key_count: None,
-            store: Box::new(MemoryStore::new()),
+            // store: Box::new(MemoryStore::new()),
+            sessions: SessionStore::new(),
             inbound_group_sessions: GroupSessionStore::new(),
         })
     }
@@ -120,7 +123,8 @@ impl OlmMachine {
             device_id: device_id.to_owned(),
             account: Arc::new(Mutex::new(account)),
             uploaded_signed_key_count: None,
-            store: Box::new(store),
+            // store: Box::new(store),
+            sessions: SessionStore::new(),
             inbound_group_sessions: GroupSessionStore::new(),
         })
     }
@@ -175,7 +179,7 @@ impl OlmMachine {
         account.mark_keys_as_published();
         drop(account);
 
-        self.store.save_account(self.account.clone()).await?;
+        // self.store.save_account(self.account.clone()).await?;
         Ok(())
     }