diff --git a/Cargo.lock b/Cargo.lock
index 8a5d033..224f89d 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -179,6 +179,7 @@ dependencies = [
  "num-traits",
  "parking_lot",
  "sexp",
+ "spin_sleep",
  "thiserror",
 ]
 
@@ -898,9 +899,6 @@ dependencies = [
 [[package]]
 name = "sexp"
 version = "1.1.4"
-dependencies = [
- "log",
-]
 
 [[package]]
 name = "sha-1"
@@ -933,6 +931,16 @@ version = "1.4.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "fbee7696b84bbf3d89a1c2eccff0850e3047ed46bfcd2e92c29a2d074d57e252"
 
+[[package]]
+name = "spin_sleep"
+version = "1.0.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "2a98101bdc3833e192713c2af0b0dd2614f50d1cf1f7a97c5221b7aac052acc7"
+dependencies = [
+ "once_cell",
+ "winapi",
+]
+
 [[package]]
 name = "strsim"
 version = "0.8.0"
diff --git a/crsn/Cargo.toml b/crsn/Cargo.toml
index 41fa0ef..5a18546 100644
--- a/crsn/Cargo.toml
+++ b/crsn/Cargo.toml
@@ -14,3 +14,4 @@ log = "0.4.11"
 num-traits = "0.2.12"
 parking_lot = "0.11.0"
 nudge = "0.2.1"
+spin_sleep = "1.0.0"
diff --git a/crsn/crsn-sexp/Cargo.toml b/crsn/crsn-sexp/Cargo.toml
index 6c03b9f..3c844bf 100644
--- a/crsn/crsn-sexp/Cargo.toml
+++ b/crsn/crsn-sexp/Cargo.toml
@@ -11,4 +11,3 @@ description = "A small, simple, self-contained, s-expression parser and pretty-p
 license = "MIT"
 
 [dependencies]
-log = "0.4.11"
diff --git a/crsn/crsn-sexp/src/lib.rs b/crsn/crsn-sexp/src/lib.rs
index 24485c4..5a360ae 100644
--- a/crsn/crsn-sexp/src/lib.rs
+++ b/crsn/crsn-sexp/src/lib.rs
@@ -4,9 +4,6 @@
 
 #![deny(unsafe_code)]
 
-#[macro_use]
-extern crate log;
-
 use std::borrow::Cow;
 use std::fmt;
 use std::str::{self, FromStr};
diff --git a/crsn/src/runtime/run_thread.rs b/crsn/src/runtime/run_thread.rs
index 9755cb9..baecf59 100644
--- a/crsn/src/runtime/run_thread.rs
+++ b/crsn/src/runtime/run_thread.rs
@@ -1,7 +1,7 @@
 use std::sync::Arc;
 
 use std::thread::JoinHandle;
-use std::time::Duration;
+use std::time::{Duration};
 
 pub use info::ThreadInfo;
 pub use state::RunState;
@@ -66,11 +66,16 @@ impl RunThread {
 
     /// Start synchronously
     pub fn run(mut self) {
+        let mut loop_helper = spin_sleep::LoopHelper::builder()
+            .build_with_target_rate(1.0/self.info.cycle_time.as_secs_f64());
+
+        loop_helper.loop_start();
         'run: loop {
             match self.eval_op() {
                 Ok(EvalRes { cycles, advance }) => {
-                    if cycles > 0 {
-                        std::thread::sleep(self.info.cycle_time * (cycles as u32));
+                    for _ in 0..cycles {
+                        loop_helper.loop_sleep();
+                        loop_helper.loop_start();
                     }
                     trace!("Step {}; Status = {}", advance, self.state.frame.status);
                     self.state.frame.pc.advance(advance);
diff --git a/launcher/src/main.rs b/launcher/src/main.rs
index 956c3f2..ea0a278 100644
--- a/launcher/src/main.rs
+++ b/launcher/src/main.rs
@@ -92,22 +92,8 @@ impl AppConfig for Config {
                 clap::Arg::with_name("cycle")
                     .long("cycle")
                     .short("C")
-                    .value_name("MILLIS")
-                    .help("Cycle time (ms)")
-                    .validator(|s| {
-                        let t = s.trim();
-                        if t.is_empty() {
-                            Err("cycle time requires an argument".into())
-                        } else {
-                            if t.chars()
-                                .find(|c| !c.is_ascii_digit())
-                                .is_some() {
-                                Err("cycle time requires an integer number".into())
-                            } else {
-                                Ok(())
-                            }
-                        }
-                    })
+                    .value_name("MICROS")
+                    .help("Cycle time (us, append \"s\" or \"ms\" for coarser time)")
                     .takes_value(true),
             )
     }
@@ -115,8 +101,23 @@ impl AppConfig for Config {
     fn configure(mut self, clap: &ArgMatches) -> anyhow::Result<Self> {
         self.program_file = clap.value_of("input").unwrap().to_string();
         self.assemble_only = clap.is_present("asm-only");
-        if let Some(c) = clap.value_of("cycle") {
-            self.cycle_time = Duration::from_millis(c.parse().unwrap());
+        if let Some(t) = clap.value_of("cycle") {
+            let (t, mul) = if t.ends_with("us") {
+                (&t[..(t.len()-2)], 1)
+            } else if t.ends_with("ms") {
+                (&t[..(t.len()-2)], 1000)
+            } else if t.ends_with("m") {
+                (&t[..(t.len()-1)], 1000)
+            } else if t.ends_with("u") {
+                (&t[..(t.len()-1)], 1)
+            } else if t.ends_with("s") {
+                (&t[..(t.len()-1)], 1000_000)
+            } else {
+                (t, 1)
+            };
+
+            self.cycle_time = Duration::from_micros(t.parse::<u64>().expect("parse -C value") * mul);
+            println!("ct = {:?}", self.cycle_time);
         }
         Ok(self)
     }