diff --git a/core/src/channel/mod.rs b/core/src/channel/mod.rs
index 67fa4b9..9aad6f5 100644
--- a/core/src/channel/mod.rs
+++ b/core/src/channel/mod.rs
@@ -272,22 +272,6 @@ impl VoiceChannel {
     }
 
     fn push_key_events_and_render(&mut self, out: &mut [f32]) {
-        fn render_for_key(
-            key: &mut Key,
-            len: usize,
-            control: &VoiceControlData,
-            params: &VoiceChannelParams,
-        ) {
-            for e in key.event_cache.drain(..) {
-                key.data
-                    .send_event(e, control, &params.channel_sf, params.layers);
-            }
-
-            prepapre_cache_vec(&mut key.audio_cache, len, 0.0);
-
-            key.data.render_to(&mut key.audio_cache);
-        }
-
         self.params
             .channel_sf
             .change_program(self.control_event_data.bank, self.control_event_data.preset);
@@ -301,7 +285,13 @@ impl VoiceChannel {
                 let control_data = &self.voice_control_data;
                 pool.install(|| {
                     key_voices.par_iter_mut().for_each(move |key| {
-                        render_for_key(key, len, control_data, params);
+                        for e in key.event_cache.drain(..) {
+                            key.data
+                                .send_event(e, control_data, &params.channel_sf, params.layers);
+                        }
+
+                        prepapre_cache_vec(&mut key.audio_cache, len, 0.0);
+                        key.data.render_to(&mut key.audio_cache);
                     });
                 });
 
@@ -310,14 +300,17 @@ impl VoiceChannel {
                 }
             }
             None => {
-                let len = out.len();
-
                 for key in self.key_voices.iter_mut() {
-                    render_for_key(key, len, &self.voice_control_data, &self.params);
-                }
+                    for e in key.event_cache.drain(..) {
+                        key.data.send_event(
+                            e,
+                            &self.voice_control_data,
+                            &self.params.channel_sf,
+                            self.params.layers,
+                        );
+                    }
 
-                for key in self.key_voices.iter() {
-                    sum_simd(&key.audio_cache, out);
+                    key.data.render_to(out);
                 }
             }
         }
diff --git a/core/src/channel_group/mod.rs b/core/src/channel_group/mod.rs
index 06630f7..370e288 100644
--- a/core/src/channel_group/mod.rs
+++ b/core/src/channel_group/mod.rs
@@ -2,7 +2,7 @@ use std::sync::Arc;
 
 use crate::{
     channel::{ChannelAudioEvent, ChannelEvent, VoiceChannel},
-    helpers::sum_simd,
+    helpers::{prepapre_cache_vec, sum_simd},
     AudioPipe, AudioStreamParams,
 };
 
@@ -36,7 +36,7 @@ impl ChannelGroup {
         let mut sample_cache_vecs = Vec::new();
 
         // Thread pool for individual channels to split between keys
-        let channel_pool = match config.parallelism.channel {
+        let channel_pool = match config.parallelism.key {
             ThreadCount::None => None,
             ThreadCount::Auto => Some(Arc::new(rayon::ThreadPoolBuilder::new().build().unwrap())),
             ThreadCount::Manual(threads) => Some(Arc::new(
@@ -48,7 +48,7 @@ impl ChannelGroup {
         };
 
         // Thread pool for splitting channels between threads
-        let group_pool = match config.parallelism.key {
+        let group_pool = match config.parallelism.channel {
             ThreadCount::None => None,
             ThreadCount::Auto => Some(rayon::ThreadPoolBuilder::new().build().unwrap()),
             ThreadCount::Manual(threads) => Some(
@@ -149,6 +149,7 @@ impl ChannelGroup {
 
         match self.thread_pool.as_ref() {
             Some(pool) => {
+                let len = buffer.len();
                 let channels = &mut self.channels;
                 let sample_cache_vecs = &mut self.sample_cache_vecs;
                 pool.install(move || {
@@ -156,13 +157,12 @@ impl ChannelGroup {
                         .par_iter_mut()
                         .zip(sample_cache_vecs.par_iter_mut())
                         .for_each(|(channel, samples)| {
-                            samples.resize(buffer.len(), 0.0);
+                            prepapre_cache_vec(samples, len, 0.0);
                             channel.read_samples(samples.as_mut_slice());
                         });
 
                     for vec in sample_cache_vecs.iter_mut() {
                         sum_simd(vec, buffer);
-                        vec.clear();
                     }
                 });
             }
@@ -174,13 +174,12 @@ impl ChannelGroup {
                     .iter_mut()
                     .zip(self.sample_cache_vecs.iter_mut())
                 {
-                    samples.resize(len, 0.0);
+                    prepapre_cache_vec(samples, len, 0.0);
                     channel.read_samples(samples.as_mut_slice());
                 }
 
                 for vec in self.sample_cache_vecs.iter_mut() {
                     sum_simd(vec, buffer);
-                    vec.clear();
                 }
             }
         }