diff --git a/crates/nu-cli/src/completions/base.rs b/crates/nu-cli/src/completions/base.rs
index cf13dae68c..68f10a7387 100644
--- a/crates/nu-cli/src/completions/base.rs
+++ b/crates/nu-cli/src/completions/base.rs
@@ -12,7 +12,7 @@ pub trait Completer {
         &mut self,
         working_set: &StateWorkingSet,
         stack: &Stack,
-        prefix: Vec<u8>,
+        prefix: &[u8],
         span: Span,
         offset: usize,
         pos: usize,
diff --git a/crates/nu-cli/src/completions/command_completions.rs b/crates/nu-cli/src/completions/command_completions.rs
index e5c7e8f140..0086270ac5 100644
--- a/crates/nu-cli/src/completions/command_completions.rs
+++ b/crates/nu-cli/src/completions/command_completions.rs
@@ -158,7 +158,7 @@ impl Completer for CommandCompletion {
         &mut self,
         working_set: &StateWorkingSet,
         _stack: &Stack,
-        prefix: Vec<u8>,
+        prefix: &[u8],
         span: Span,
         offset: usize,
         pos: usize,
@@ -195,7 +195,7 @@ impl Completer for CommandCompletion {
         };
 
         if !subcommands.is_empty() {
-            return sort_suggestions(&String::from_utf8_lossy(&prefix), subcommands, options);
+            return sort_suggestions(&String::from_utf8_lossy(prefix), subcommands, options);
         }
 
         let config = working_set.get_config();
@@ -220,7 +220,7 @@ impl Completer for CommandCompletion {
             vec![]
         };
 
-        sort_suggestions(&String::from_utf8_lossy(&prefix), commands, options)
+        sort_suggestions(&String::from_utf8_lossy(prefix), commands, options)
     }
 }
 
diff --git a/crates/nu-cli/src/completions/completer.rs b/crates/nu-cli/src/completions/completer.rs
index 2845445b44..555d14ff27 100644
--- a/crates/nu-cli/src/completions/completer.rs
+++ b/crates/nu-cli/src/completions/completer.rs
@@ -38,7 +38,7 @@ impl NuCompleter {
         &self,
         completer: &mut T,
         working_set: &StateWorkingSet,
-        prefix: Vec<u8>,
+        prefix: &[u8],
         new_span: Span,
         offset: usize,
         pos: usize,
@@ -55,7 +55,7 @@ impl NuCompleter {
         completer.fetch(
             working_set,
             &self.stack,
-            prefix.clone(),
+            prefix,
             new_span,
             offset,
             pos,
@@ -170,9 +170,9 @@ impl NuCompleter {
                         let new_span = Span::new(flat.0.start, flat.0.end - 1);
 
                         // Parses the prefix. Completion should look up to the cursor position, not after.
-                        let mut prefix = working_set.get_span_contents(flat.0).to_vec();
+                        let mut prefix = working_set.get_span_contents(flat.0);
                         let index = pos - flat.0.start;
-                        prefix.drain(index..);
+                        prefix = &prefix[..index];
 
                         // Variables completion
                         if prefix.starts_with(b"$") || most_left_var.is_some() {
@@ -182,7 +182,7 @@ impl NuCompleter {
                             let mut variable_completions = self.process_completion(
                                 &mut variable_names_completer,
                                 &working_set,
-                                prefix.clone(),
+                                prefix,
                                 new_span,
                                 fake_offset,
                                 pos,
@@ -211,7 +211,7 @@ impl NuCompleter {
                             let result = self.process_completion(
                                 &mut completer,
                                 &working_set,
-                                prefix.clone(),
+                                prefix,
                                 new_span,
                                 fake_offset,
                                 pos,
@@ -362,7 +362,7 @@ impl NuCompleter {
                                 let mut out: Vec<_> = self.process_completion(
                                     &mut completer,
                                     &working_set,
-                                    prefix.clone(),
+                                    prefix,
                                     new_span,
                                     fake_offset,
                                     pos,
diff --git a/crates/nu-cli/src/completions/completion_common.rs b/crates/nu-cli/src/completions/completion_common.rs
index 438ce2a1f0..fc7a5fcd2c 100644
--- a/crates/nu-cli/src/completions/completion_common.rs
+++ b/crates/nu-cli/src/completions/completion_common.rs
@@ -335,7 +335,7 @@ pub fn sort_completions<T>(
         } else {
             matcher = matcher.ignore_case();
         };
-        items.sort_by(|a, b| {
+        items.sort_unstable_by(|a, b| {
             let a_str = get_value(a);
             let b_str = get_value(b);
             let a_score = matcher.fuzzy_match(a_str, prefix).unwrap_or_default();
@@ -343,7 +343,7 @@ pub fn sort_completions<T>(
             b_score.cmp(&a_score).then(a_str.cmp(b_str))
         });
     } else {
-        items.sort_by(|a, b| get_value(a).cmp(get_value(b)));
+        items.sort_unstable_by(|a, b| get_value(a).cmp(get_value(b)));
     }
 
     items
diff --git a/crates/nu-cli/src/completions/custom_completions.rs b/crates/nu-cli/src/completions/custom_completions.rs
index 817c7aec47..b6098bc85d 100644
--- a/crates/nu-cli/src/completions/custom_completions.rs
+++ b/crates/nu-cli/src/completions/custom_completions.rs
@@ -35,7 +35,7 @@ impl Completer for CustomCompletion {
         &mut self,
         working_set: &StateWorkingSet,
         _stack: &Stack,
-        prefix: Vec<u8>,
+        prefix: &[u8],
         span: Span,
         offset: usize,
         pos: usize,
@@ -126,8 +126,8 @@ impl Completer for CustomCompletion {
         let options = custom_completion_options
             .as_ref()
             .unwrap_or(completion_options);
-        let suggestions = filter(&prefix, suggestions, options);
-        sort_suggestions(&String::from_utf8_lossy(&prefix), suggestions, options)
+        let suggestions = filter(prefix, suggestions, options);
+        sort_suggestions(&String::from_utf8_lossy(prefix), suggestions, options)
     }
 }
 
diff --git a/crates/nu-cli/src/completions/directory_completions.rs b/crates/nu-cli/src/completions/directory_completions.rs
index 342cf42f4e..ea8eb89871 100644
--- a/crates/nu-cli/src/completions/directory_completions.rs
+++ b/crates/nu-cli/src/completions/directory_completions.rs
@@ -26,13 +26,13 @@ impl Completer for DirectoryCompletion {
         &mut self,
         working_set: &StateWorkingSet,
         stack: &Stack,
-        prefix: Vec<u8>,
+        prefix: &[u8],
         span: Span,
         offset: usize,
         _pos: usize,
         options: &CompletionOptions,
     ) -> Vec<SemanticSuggestion> {
-        let AdjustView { prefix, span, .. } = adjust_if_intermediate(&prefix, working_set, span);
+        let AdjustView { prefix, span, .. } = adjust_if_intermediate(prefix, working_set, span);
 
         // Filter only the folders
         #[allow(deprecated)]
diff --git a/crates/nu-cli/src/completions/dotnu_completions.rs b/crates/nu-cli/src/completions/dotnu_completions.rs
index 4a241a57b9..482c5c1d18 100644
--- a/crates/nu-cli/src/completions/dotnu_completions.rs
+++ b/crates/nu-cli/src/completions/dotnu_completions.rs
@@ -22,13 +22,13 @@ impl Completer for DotNuCompletion {
         &mut self,
         working_set: &StateWorkingSet,
         stack: &Stack,
-        prefix: Vec<u8>,
+        prefix: &[u8],
         span: Span,
         offset: usize,
         _pos: usize,
         options: &CompletionOptions,
     ) -> Vec<SemanticSuggestion> {
-        let prefix_str = String::from_utf8_lossy(&prefix).replace('`', "");
+        let prefix_str = String::from_utf8_lossy(prefix).replace('`', "");
         let mut search_dirs: Vec<String> = vec![];
 
         // If prefix_str is only a word we want to search in the current dir
diff --git a/crates/nu-cli/src/completions/file_completions.rs b/crates/nu-cli/src/completions/file_completions.rs
index 16e0c09b5c..42e1d397ea 100644
--- a/crates/nu-cli/src/completions/file_completions.rs
+++ b/crates/nu-cli/src/completions/file_completions.rs
@@ -27,7 +27,7 @@ impl Completer for FileCompletion {
         &mut self,
         working_set: &StateWorkingSet,
         stack: &Stack,
-        prefix: Vec<u8>,
+        prefix: &[u8],
         span: Span,
         offset: usize,
         _pos: usize,
@@ -37,7 +37,7 @@ impl Completer for FileCompletion {
             prefix,
             span,
             readjusted,
-        } = adjust_if_intermediate(&prefix, working_set, span);
+        } = adjust_if_intermediate(prefix, working_set, span);
 
         #[allow(deprecated)]
         let items: Vec<_> = complete_item(
diff --git a/crates/nu-cli/src/completions/flag_completions.rs b/crates/nu-cli/src/completions/flag_completions.rs
index 590929d5a0..57cd691082 100644
--- a/crates/nu-cli/src/completions/flag_completions.rs
+++ b/crates/nu-cli/src/completions/flag_completions.rs
@@ -24,7 +24,7 @@ impl Completer for FlagCompletion {
         &mut self,
         working_set: &StateWorkingSet,
         _stack: &Stack,
-        prefix: Vec<u8>,
+        prefix: &[u8],
         span: Span,
         offset: usize,
         _pos: usize,
@@ -44,7 +44,7 @@ impl Completer for FlagCompletion {
                     short.encode_utf8(&mut named);
                     named.insert(0, b'-');
 
-                    if options.match_algorithm.matches_u8(&named, &prefix) {
+                    if options.match_algorithm.matches_u8(&named, prefix) {
                         output.push(SemanticSuggestion {
                             suggestion: Suggestion {
                                 value: String::from_utf8_lossy(&named).to_string(),
@@ -70,7 +70,7 @@ impl Completer for FlagCompletion {
                 named.insert(0, b'-');
                 named.insert(0, b'-');
 
-                if options.match_algorithm.matches_u8(&named, &prefix) {
+                if options.match_algorithm.matches_u8(&named, prefix) {
                     output.push(SemanticSuggestion {
                         suggestion: Suggestion {
                             value: String::from_utf8_lossy(&named).to_string(),
@@ -88,7 +88,7 @@ impl Completer for FlagCompletion {
                 }
             }
 
-            return sort_suggestions(&String::from_utf8_lossy(&prefix), output, options);
+            return sort_suggestions(&String::from_utf8_lossy(prefix), output, options);
         }
 
         vec![]
diff --git a/crates/nu-cli/src/completions/operator_completions.rs b/crates/nu-cli/src/completions/operator_completions.rs
index c670988a29..e9e95d0799 100644
--- a/crates/nu-cli/src/completions/operator_completions.rs
+++ b/crates/nu-cli/src/completions/operator_completions.rs
@@ -24,7 +24,7 @@ impl Completer for OperatorCompletion {
         &mut self,
         working_set: &StateWorkingSet,
         _stack: &Stack,
-        _prefix: Vec<u8>,
+        _prefix: &[u8],
         span: Span,
         offset: usize,
         _pos: usize,
diff --git a/crates/nu-cli/src/completions/variable_completions.rs b/crates/nu-cli/src/completions/variable_completions.rs
index 5e8f117810..29b5393257 100644
--- a/crates/nu-cli/src/completions/variable_completions.rs
+++ b/crates/nu-cli/src/completions/variable_completions.rs
@@ -27,7 +27,7 @@ impl Completer for VariableCompletion {
         &mut self,
         working_set: &StateWorkingSet,
         stack: &Stack,
-        prefix: Vec<u8>,
+        prefix: &[u8],
         span: Span,
         offset: usize,
         _pos: usize,
@@ -42,7 +42,7 @@ impl Completer for VariableCompletion {
             end: span.end - offset,
         };
         let sublevels_count = self.var_context.1.len();
-        let prefix_str = String::from_utf8_lossy(&prefix);
+        let prefix_str = String::from_utf8_lossy(prefix);
 
         // Completions for the given variable
         if !var_str.is_empty() {
@@ -66,7 +66,7 @@ impl Completer for VariableCompletion {
                             if options.match_algorithm.matches_u8_insensitive(
                                 options.case_sensitive,
                                 suggestion.suggestion.value.as_bytes(),
-                                &prefix,
+                                prefix,
                             ) {
                                 output.push(suggestion);
                             }
@@ -80,7 +80,7 @@ impl Completer for VariableCompletion {
                         if options.match_algorithm.matches_u8_insensitive(
                             options.case_sensitive,
                             env_var.0.as_bytes(),
-                            &prefix,
+                            prefix,
                         ) {
                             output.push(SemanticSuggestion {
                                 suggestion: Suggestion {
@@ -111,7 +111,7 @@ impl Completer for VariableCompletion {
                         if options.match_algorithm.matches_u8_insensitive(
                             options.case_sensitive,
                             suggestion.suggestion.value.as_bytes(),
-                            &prefix,
+                            prefix,
                         ) {
                             output.push(suggestion);
                         }
@@ -133,7 +133,7 @@ impl Completer for VariableCompletion {
                         if options.match_algorithm.matches_u8_insensitive(
                             options.case_sensitive,
                             suggestion.suggestion.value.as_bytes(),
-                            &prefix,
+                            prefix,
                         ) {
                             output.push(suggestion);
                         }
@@ -149,7 +149,7 @@ impl Completer for VariableCompletion {
             if options.match_algorithm.matches_u8_insensitive(
                 options.case_sensitive,
                 builtin.as_bytes(),
-                &prefix,
+                prefix,
             ) {
                 output.push(SemanticSuggestion {
                     suggestion: Suggestion {
@@ -173,7 +173,7 @@ impl Completer for VariableCompletion {
                     if options.match_algorithm.matches_u8_insensitive(
                         options.case_sensitive,
                         v.0,
-                        &prefix,
+                        prefix,
                     ) {
                         output.push(SemanticSuggestion {
                             suggestion: Suggestion {
@@ -201,7 +201,7 @@ impl Completer for VariableCompletion {
                 if options.match_algorithm.matches_u8_insensitive(
                     options.case_sensitive,
                     v.0,
-                    &prefix,
+                    prefix,
                 ) {
                     output.push(SemanticSuggestion {
                         suggestion: Suggestion {