diff --git a/schala-repl/src/language.rs b/schala-repl/src/language.rs
index 3ea7f4f..d3e552f 100644
--- a/schala-repl/src/language.rs
+++ b/schala-repl/src/language.rs
@@ -9,6 +9,7 @@ pub struct LLVMCodeString(pub String);
 pub struct EvalOptions {
   pub execution_method: ExecutionMethod,
   pub debug_passes: HashMap<String, PassDebugOptionsDescriptor>,
+  pub debug_timing: bool,
 }
 
 #[derive(Debug, Hash, PartialEq)]
@@ -55,7 +56,7 @@ impl UnfinishedComputation {
     FinishedComputation {
       artifacts: self.artifacts,
       text_output,
-      durations: self.durations
+      durations: self.durations,
     }
   }
   pub fn output(self, output: Result<String, String>) -> FinishedComputation {
@@ -68,6 +69,22 @@ impl UnfinishedComputation {
 }
 
 impl FinishedComputation {
+
+  fn get_timing(&self) -> Option<String> {
+    if self.durations.len() != 0 {
+      let mut buf = String::new();
+      write!(&mut buf, "Timing: ").unwrap();
+      for duration in self.durations.iter() {
+        let timing = (duration.as_secs() as f64) + (duration.subsec_nanos() as f64 * 1e-9);
+        write!(&mut buf, "{}s, ", timing).unwrap()
+      }
+      write!(&mut buf, "\n").unwrap();
+      Some(buf)
+    } else {
+      None
+    }
+  }
+
   pub fn to_repl(&self) -> String {
     let mut buf = String::new();
     for (stage, artifact) in self.artifacts.iter() {
@@ -77,15 +94,11 @@ impl FinishedComputation {
       write!(&mut buf, "{}: {}\n", stage, output).unwrap();
     }
 
-    let debug_timing = true;
-    if debug_timing {
-      write!(&mut buf, "Timing: ").unwrap();
-      for duration in self.durations.iter() {
-        let timing = (duration.as_secs() as f64) + (duration.subsec_nanos() as f64 * 1e-9);
-        write!(&mut buf, "{}s, ", timing).unwrap()
-      }
-      write!(&mut buf, "\n").unwrap();
+    match self.get_timing() {
+      Some(timing) => write!(&mut buf, "{}", timing).unwrap(),
+      None => ()
     }
+
     match self.text_output {
       Ok(ref output) => write!(&mut buf, "{}", output).unwrap(),
       Err(ref err) => write!(&mut buf, "{} {}", "Error: ".red().bold(), err).unwrap(),
@@ -169,23 +182,23 @@ pub trait ProgrammingLanguageInterface {
 
 #[macro_export]
 macro_rules! pass_chain {
-  ($state:expr, $options:expr; $($pass:path), *) => {
+  ($state:expr, $eval_options:expr; $($pass:path), *) => {
     |text_input| {
       let mut comp = UnfinishedComputation::default();
-      pass_chain_helper! { ($state, comp, $options); text_input $(, $pass)* }
+      pass_chain_helper! { ($state, comp, $eval_options); text_input $(, $pass)* }
     }
   };
 }
 
 #[macro_export]
 macro_rules! pass_chain_helper {
-  (($state:expr, $comp:expr, $options:expr); $input:expr, $pass:path $(, $rest:path)*) => {
+  (($state:expr, $comp:expr, $eval_options:expr); $input:expr, $pass:path $(, $rest:path)*) => {
     {
       use std::time;
       use schala_repl::PassDebugOptionsDescriptor;
       let pass_name = stringify!($pass);
       let (output, duration) = {
-        let ref debug_map = $options.debug_passes;
+        let ref debug_map = $eval_options.debug_passes;
         let debug_handle = match debug_map.get(pass_name) {
           Some(PassDebugOptionsDescriptor { opts }) => {
             let ptr = &mut $comp;
@@ -199,9 +212,11 @@ macro_rules! pass_chain_helper {
         let elapsed = start.elapsed();
         (pass_output, elapsed)
       };
-      $comp.durations.push(duration);
+      if $eval_options.debug_timing {
+        $comp.durations.push(duration);
+      }
       match output {
-        Ok(result) => pass_chain_helper! { ($state, $comp, $options); result $(, $rest)* },
+        Ok(result) => pass_chain_helper! { ($state, $comp, $eval_options); result $(, $rest)* },
         Err(err) => {
           $comp.output(Err(format!("Pass {} failed with {:?}", pass_name, err)))
         }
@@ -209,7 +224,7 @@ macro_rules! pass_chain_helper {
     }
   };
   // Done
-  (($state:expr, $comp:expr, $options:expr); $final_output:expr) => {
+  (($state:expr, $comp:expr, $eval_options:expr); $final_output:expr) => {
     {
       let final_output: FinishedComputation = $comp.finish(Ok($final_output));
       final_output
diff --git a/schala-repl/src/repl.rs b/schala-repl/src/repl.rs
index 8d3e78a..a66ea79 100644
--- a/schala-repl/src/repl.rs
+++ b/schala-repl/src/repl.rs
@@ -134,7 +134,11 @@ impl Repl {
         CommandTree::term("passes", None),
         CommandTree::NonTerminal(format!("show"), passes_directives.clone(), None),
         CommandTree::NonTerminal(format!("hide"), passes_directives.clone(), None),
-      ], Some(format!("show or hide pass info for a given pass, or display the names of all passes"))),
+        CommandTree::NonTerminal(format!("timing"), vec![
+          CommandTree::term("on", None),
+          CommandTree::term("off", None),
+        ], None),
+      ], Some(format!("show or hide pass debug info for a given pass, or display the names of all passes, or turn timing on/off"))),
       CommandTree::NonTerminal(format!("lang"), vec![
         CommandTree::term("next", None),
         CommandTree::term("prev", None),
@@ -228,6 +232,11 @@ impl Repl {
   fn handle_debug(&mut self, commands: Vec<&str>) -> Option<String> {
     let passes = self.get_cur_language().get_passes();
     match commands.get(1) {
+      Some(&"timing") => match commands.get(2) {
+        Some(&"on") => { self.options.debug_timing = true; None }
+        Some(&"off") => { self.options.debug_timing = false; None }
+        _ => return Some(format!(r#"Argument to "timing" must be "on" or "off""#)),
+      },
       Some(&"passes") => Some(
         passes.into_iter()
         .map(|desc| {