diff --git a/packages/core/cyclist.mjs b/packages/core/cyclist.mjs
index 9b522f05..6e8171ea 100644
--- a/packages/core/cyclist.mjs
+++ b/packages/core/cyclist.mjs
@@ -10,44 +10,49 @@ import { logger } from './logger.mjs';
 export class Cyclist {
   constructor({ interval, onTrigger, onToggle, onError, getTime, latency = 0.1 }) {
     this.started = false;
-    this.cps = 1; // TODO
-    this.phase = 0;
-    this.getTime = getTime;
+    this.cps = 1;
+    this.lastTick = 0; // absolute time when last tick (clock callback) happened
+    this.lastBegin = 0; // query begin of last tick
+    this.lastEnd = 0; // query end of last tick
+    this.getTime = getTime; // get absolute time
     this.onToggle = onToggle;
-    this.latency = latency;
+    this.latency = latency; // fixed trigger time offset
     const round = (x) => Math.round(x * 1000) / 1000;
     this.clock = createClock(
       getTime,
+      // called slightly before each cycle
       (phase, duration, tick) => {
         if (tick === 0) {
           this.origin = phase;
         }
-        const begin = round(phase - this.origin);
-        this.phase = begin - latency;
-        const end = round(begin + duration);
-        const time = getTime();
         try {
-          const haps = this.pattern.queryArc(begin, end); // get Haps
+          const time = getTime();
+          const begin = this.lastEnd;
+          this.lastBegin = begin;
+          const end = round(begin + duration * this.cps);
+          this.lastEnd = end;
+          const haps = this.pattern.queryArc(begin, end);
+          const tickdeadline = phase - time; // time left till phase begins
+          this.lastTick = time + tickdeadline;
+
           haps.forEach((hap) => {
             if (hap.part.begin.equals(hap.whole.begin)) {
-              const deadline = hap.whole.begin + this.origin - time + latency;
-              const duration = hap.duration * 1;
-              onTrigger?.(hap, deadline, duration);
+              const deadline = (hap.whole.begin - begin) / this.cps + tickdeadline + latency;
+              const duration = hap.duration / this.cps;
+              onTrigger?.(hap, deadline, duration, this.cps);
             }
           });
         } catch (e) {
           logger(`[cyclist] error: ${e.message}`);
           onError?.(e);
         }
-      }, // called slightly before each cycle
+      },
       interval, // duration of each cycle
     );
   }
-  getPhase() {
-    return this.getTime() - this.origin - this.latency;
-  }
   now() {
-    return this.getTime() - this.origin + this.clock.minLatency;
+    const secondsSinceLastTick = this.getTime() - this.lastTick - this.clock.duration;
+    return this.lastBegin + secondsSinceLastTick * this.cps; // + this.clock.minLatency;
   }
   setStarted(v) {
     this.started = v;
diff --git a/packages/core/evaluate.mjs b/packages/core/evaluate.mjs
index 3379824e..1d7be8e4 100644
--- a/packages/core/evaluate.mjs
+++ b/packages/core/evaluate.mjs
@@ -6,12 +6,7 @@ This program is free software: you can redistribute it and/or modify it under th
 
 import { isPattern } from './index.mjs';
 
-let scoped = false;
 export const evalScope = async (...args) => {
-  if (scoped) {
-    console.warn('evalScope was called more than once.');
-  }
-  scoped = true;
   const results = await Promise.allSettled(args);
   const modules = results.filter((result) => result.status === 'fulfilled').map((r) => r.value);
   results.forEach((result, i) => {
@@ -42,9 +37,6 @@ function safeEval(str, options = {}) {
 }
 
 export const evaluate = async (code, transpiler) => {
-  if (!scoped) {
-    await evalScope(); // at least scope Pattern.prototype.boostrap
-  }
   if (transpiler) {
     code = transpiler(code); // transform syntactically correct js code to semantically usable code
   }
diff --git a/packages/core/repl.mjs b/packages/core/repl.mjs
index 045f2102..b5d8cb92 100644
--- a/packages/core/repl.mjs
+++ b/packages/core/repl.mjs
@@ -2,6 +2,7 @@ import { Cyclist } from './cyclist.mjs';
 import { evaluate as _evaluate } from './evaluate.mjs';
 import { logger } from './logger.mjs';
 import { setTime } from './time.mjs';
+import { evalScope } from './evaluate.mjs';
 
 export function repl({
   interval,
@@ -17,13 +18,12 @@ export function repl({
 }) {
   const scheduler = new Cyclist({
     interval,
-    onTrigger: async (hap, deadline, duration) => {
+    onTrigger: async (hap, deadline, duration, cps) => {
       try {
         if (!hap.context.onTrigger || !hap.context.dominantTrigger) {
           await defaultOutput(hap, deadline, duration);
         }
         if (hap.context.onTrigger) {
-          const cps = 1;
           // call signature of output / onTrigger is different...
           await hap.context.onTrigger(getTime() + deadline, hap, getTime(), cps);
         }
@@ -42,6 +42,17 @@ export function repl({
     }
     try {
       beforeEval?.({ code });
+      scheduler.setCps(1); // reset cps in case the code does not contain a setCps call
+      // problem: when the code does contain a setCps after an awaited promise,
+      // the cps will be 1 until the promise resolves
+      // example:
+      /*
+      await new Promise(resolve => setTimeout(resolve,1000))
+      setCps(.5)
+      note("c a f e")
+      */
+      // to make sure the setCps inside the code is called immediately,
+      // it has to be placed first
       let { pattern } = await _evaluate(code, transpiler);
 
       logger(`[eval] code updated`);
@@ -58,5 +69,10 @@ export function repl({
   const stop = () => scheduler.stop();
   const start = () => scheduler.start();
   const pause = () => scheduler.pause();
-  return { scheduler, evaluate, start, stop, pause };
+  const setCps = (cps) => scheduler.setCps(cps);
+  evalScope({
+    setCps,
+    setcps: setCps,
+  });
+  return { scheduler, evaluate, start, stop, pause, setCps };
 }
diff --git a/packages/core/zyklus.mjs b/packages/core/zyklus.mjs
index e66d8e2e..3d25b054 100644
--- a/packages/core/zyklus.mjs
+++ b/packages/core/zyklus.mjs
@@ -44,6 +44,6 @@ function createClock(
   };
   const getPhase = () => phase;
   // setCallback
-  return { setDuration, start, stop, pause, duration, getPhase, minLatency };
+  return { setDuration, start, stop, pause, duration, interval, getPhase, minLatency };
 }
 export default createClock;
diff --git a/packages/react/src/hooks/useHighlighting.mjs b/packages/react/src/hooks/useHighlighting.mjs
index 6e336586..4ce2a936 100644
--- a/packages/react/src/hooks/useHighlighting.mjs
+++ b/packages/react/src/hooks/useHighlighting.mjs
@@ -1,5 +1,6 @@
 import { useEffect, useRef } from 'react';
 import { setHighlights } from '../components/CodeMirror6';
+const round = (x) => Math.round(x * 1000) / 1000;
 
 function useHighlighting({ view, pattern, active, getTime }) {
   const highlights = useRef([]);
@@ -14,7 +15,7 @@ function useHighlighting({ view, pattern, active, getTime }) {
             // force min framerate of 10 fps => fixes crash on tab refocus, where lastEnd could be far away
             // see https://github.com/tidalcycles/strudel/issues/108
             const begin = Math.max(lastEnd.current ?? audioTime, audioTime - 1 / 10, -0.01); // negative time seems buggy
-            const span = [begin, audioTime + 1 / 60];
+            const span = [round(begin), round(audioTime + 1 / 60)];
             lastEnd.current = span[1];
             highlights.current = highlights.current.filter((hap) => hap.whole.end > audioTime); // keep only highlights that are still active
             const haps = pattern.queryArc(...span).filter((hap) => hap.hasOnset());
diff --git a/packages/react/src/hooks/useStrudel.mjs b/packages/react/src/hooks/useStrudel.mjs
index b0b1062c..0900ebbf 100644
--- a/packages/react/src/hooks/useStrudel.mjs
+++ b/packages/react/src/hooks/useStrudel.mjs
@@ -32,7 +32,7 @@ function useStrudel({
   const shouldPaint = useCallback((pat) => !!(pat?.context?.onPaint && drawContext), [drawContext]);
 
   // TODO: make sure this hook reruns when scheduler.started changes
-  const { scheduler, evaluate, start, stop, pause } = useMemo(
+  const { scheduler, evaluate, start, stop, pause, setCps } = useMemo(
     () =>
       repl({
         interval,
@@ -153,6 +153,7 @@ function useStrudel({
     stop,
     pause,
     togglePlay,
+    setCps,
   };
 }
 
diff --git a/website/src/repl/Footer.jsx b/website/src/repl/Footer.jsx
index 07bdd386..08ab967e 100644
--- a/website/src/repl/Footer.jsx
+++ b/website/src/repl/Footer.jsx
@@ -92,7 +92,7 @@ export function Footer({ context }) {
           {activeFooter === 'console' && <ConsoleTab log={log} />}
           {activeFooter === 'samples' && <SamplesTab />}
           {activeFooter === 'reference' && <Reference />}
-          {activeFooter === 'settings' && <SettingsTab />}
+          {activeFooter === 'settings' && <SettingsTab scheduler={context.scheduler} />}
         </div>
       )}
     </footer>
@@ -284,10 +284,28 @@ const fontFamilyOptions = {
   PressStart: 'PressStart2P',
 };
 
-function SettingsTab() {
+function SettingsTab({ scheduler }) {
   const { theme, keybindings, fontSize, fontFamily } = useSettings();
   return (
     <div className="text-foreground p-4 space-y-4">
+      {/* <FormItem label="Tempo">
+        <div className="space-x-4">
+          <button
+            onClick={() => {
+              scheduler.setCps(scheduler.cps - 0.1);
+            }}
+          >
+            slower
+          </button>
+          <button
+            onClick={() => {
+              scheduler.setCps(scheduler.cps + 0.1);
+            }}
+          >
+            faster
+          </button>
+        </div>
+      </FormItem> */}
       <FormItem label="Theme">
         <SelectInput options={themeOptions} value={theme} onChange={(theme) => settingsMap.setKey('theme', theme)} />
       </FormItem>
diff --git a/website/src/repl/Repl.jsx b/website/src/repl/Repl.jsx
index d73adcae..ce21f1c1 100644
--- a/website/src/repl/Repl.jsx
+++ b/website/src/repl/Repl.jsx
@@ -242,6 +242,7 @@ export function Repl({ embedded = false }) {
     }
   };
   const context = {
+    scheduler,
     embedded,
     started,
     pending,
@@ -273,7 +274,10 @@ export function Repl({ embedded = false }) {
             fontSize={fontSize}
             fontFamily={fontFamily}
             onChange={handleChangeCode}
-            onViewChanged={setView}
+            onViewChanged={(v) => {
+              setView(v);
+              // window.editorView = v;
+            }}
             onSelectionChange={handleSelectionChange}
           />
         </section>