diff --git a/src/commands/audio_output_devices/outputs.rs b/src/commands/audio_output_devices/outputs.rs
index b1ec470..a9c978a 100644
--- a/src/commands/audio_output_devices/outputs.rs
+++ b/src/commands/audio_output_devices/outputs.rs
@@ -34,7 +34,10 @@ impl CommandResponse for OutputsResponse {
     }
 
     fn parse(parts: ResponseAttributes<'_>) -> Result<Self, ResponseParserError> {
-        let mut outputs = Vec::new();
+        let parts = parts.into_vec()?;
+
+        let result_len = parts.iter().filter(|(k, _)| *k == "outputid").count();
+        let mut outputs = Vec::with_capacity(result_len);
 
         let mut id: Option<AudioOutputId> = None;
         let mut name: Option<String> = None;
@@ -42,7 +45,7 @@ impl CommandResponse for OutputsResponse {
         let mut enabled: Option<bool> = None;
         let mut attributes: HashMap<String, String> = HashMap::new();
 
-        for (k, v) in parts.into_vec()?.into_iter() {
+        for (k, v) in parts.into_iter() {
             match k {
                 "outputid" => {
                     // Reset and store the previous output if all fields are present
diff --git a/src/commands/connection_settings/protocol_disable.rs b/src/commands/connection_settings/protocol_disable.rs
index a8b26a3..e216ce9 100644
--- a/src/commands/connection_settings/protocol_disable.rs
+++ b/src/commands/connection_settings/protocol_disable.rs
@@ -38,7 +38,7 @@ impl CommandRequest for ProtocolDisableRequest {
             return Err(RequestParserError::UnexpectedEOF);
         }
 
-        let mut features = Vec::new();
+        let mut features = Vec::with_capacity(parts.size_hint().0);
         for part in parts {
             let feature = part
                 .parse()
diff --git a/src/commands/connection_settings/protocol_enable.rs b/src/commands/connection_settings/protocol_enable.rs
index 2bd5b4a..105d500 100644
--- a/src/commands/connection_settings/protocol_enable.rs
+++ b/src/commands/connection_settings/protocol_enable.rs
@@ -38,7 +38,7 @@ impl CommandRequest for ProtocolEnableRequest {
             return Err(RequestParserError::UnexpectedEOF);
         }
 
-        let mut features = Vec::new();
+        let mut features = Vec::with_capacity(parts.size_hint().0);
         for part in parts {
             let feature = part
                 .parse()
diff --git a/src/commands/stickers/stickernamestypes.rs b/src/commands/stickers/stickernamestypes.rs
index b0bff5b..0314a04 100644
--- a/src/commands/stickers/stickernamestypes.rs
+++ b/src/commands/stickers/stickernamestypes.rs
@@ -68,7 +68,8 @@ impl CommandResponse for StickerNamesTypesResponse {
 
     fn parse(parts: ResponseAttributes<'_>) -> Result<Self, ResponseParserError> {
         let parts: Vec<_> = parts.into_vec()?;
-        let mut result = HashMap::new();
+        debug_assert!(parts.len() % 2 == 0);
+        let mut result = HashMap::with_capacity(parts.len() / 2);
 
         for name_type_pair in parts.chunks_exact(2) {
             // TODO: don't depend on order, just make sure we have both