perf: avoid unnecessary clone and pre-allocate Vecs in hot paths

src/message.rs

@@ -286,7 +286,7 @@ impl Client {
 
         let unavailable_node = nr.get_optional_child("unavailable");
 
-        let mut all_enc_nodes: Vec<&NodeRef<'_>> = Vec::new();
+        let mut all_enc_nodes: Vec<&NodeRef<'_>> = Vec::with_capacity(4);
 
         let direct_enc_nodes = nr.get_children_by_tag("enc");
         all_enc_nodes.extend(direct_enc_nodes);

wacore/src/send.rs

@@ -1080,11 +1080,11 @@ pub async fn prepare_group_stanza<
         //   because they need the SKDM to decrypt messages we send from this device
         // - Exclude hosted/Cloud API devices (device ID 99 or @hosted server) - they don't
         //   participate in group E2EE, only in 1:1 chats
-        let own_user = own_sending_jid.user.clone();
+        let own_user = &own_sending_jid.user;
         let own_device = own_sending_jid.device;
         let before_filter = resolved_list.len();
         resolved_list.retain(|device_jid| {
-            let is_exact_sender = device_jid.user == own_user && device_jid.device == own_device;
+            let is_exact_sender = device_jid.user == *own_user && device_jid.device == own_device;
             let is_hosted = device_jid.is_hosted();
             // Exclude the exact sending device and hosted devices
             !is_exact_sender && !is_hosted

wacore/src/usync.rs

@@ -85,7 +85,8 @@ pub fn parse_get_user_devices_response_with_phash(resp_node: &Node) -> Result<Ve
                 _ => None,
             });
 
-        let mut devices = Vec::new();
+        let capacity = device_list_node.children().map_or(0, |c| c.len());
+        let mut devices = Vec::with_capacity(capacity);
         for device_node in device_list_node.get_children_by_tag("device") {
             let device_id_str = match device_node.attrs().optional_string("id") {
                 Some(id) => id,