REAPER Audio Workflows
REAPER CPU spikes and stuttering? How to lower CPU usage
Published August 16, 2026 · Updated September 12, 2026
Playback that stutters, crackles, or drops out while the CPU meter jumps almost always means the real-time audio load is too high for your current buffer size, usually from too many or too heavy plugins. Open the Performance Meter first (View, Performance Meter) to see your real load and which tracks are heaviest. Then raise your audio buffer, turn on anticipative FX processing, and freeze or apply the FX on the heaviest tracks. On most machines this is very fixable without buying anything.
A spiking CPU meter and stuttering playback are among the most common REAPER frustrations, and they are easy to misread. It looks like your computer is dying, but a project can glitch while your operating system says the CPU is only half busy. That is because the number that causes dropouts is not your total CPU load. It is the load on REAPER’s real-time audio thread, and that is the one you have to bring down.
The good news is that this is a settings and arrangement problem far more often than a hardware problem. You do not need a new computer to stop most stutters. You need to see where the load is coming from, give REAPER more time to do its work, and take weight off the tracks that are carrying too much. Here is how to do that with stock REAPER only.
First, know which CPU number matters
REAPER has to prepare each block of audio before your sound card asks for it. If it cannot finish a block in time, you get a gap, and that gap is what you hear as a click, a stutter, or a dropout. This deadline depends on your buffer size, not on how idle the rest of your computer is.
So a small buffer and one heavy plugin can cause dropouts even when Windows Task Manager or macOS Activity Monitor shows plenty of headroom. Do not judge the problem by the operating system’s CPU graph. Judge it by REAPER’s own meter, which reads the real-time audio load directly.
Read the Performance Meter before you change anything
Guessing at fixes is how people end up degrading their sound for no reason. Find the load first.
Open the Performance Meter
Go to View, Performance Meter. It shows REAPER’s CPU use as a percentage, along with RAM and disk activity, updating live as you play.
Watch it during the glitchy part
Play the section that stutters and watch the meter. If the CPU figure jumps toward 100% exactly when the audio breaks up, real-time load is your problem, which is the usual case.
Find the heaviest track
The Performance Meter can break the load down so you can see which tracks and plugins are using the most CPU. Note the one or two worst offenders. Those are where the fixes below pay off most.
If the meter is not spiking but you still get dropouts, one specific plugin may be misbehaving rather than your project being too heavy. Bypass plugins one at a time until the glitch stops, and you have found it.
The fixes, least destructive first
Work down this list in order. The early steps change nothing permanent, so try them before you commit to anything that alters your tracks.
1. Raise the audio buffer size
A bigger buffer gives REAPER more time to prepare each block, which is the single most effective cure for playback stutter. Go to Options, Preferences, Audio, Device and increase the requested block size to 512, 1024, or even 2048 samples. With an ASIO interface you may need to open its control panel to change the buffer there.
The trade-off is latency: a larger buffer adds a slight delay, which does not matter while mixing but does matter while recording. Keep the buffer high for mixing and playback, then lower it again when you need to track live. If your stutter only happens while recording, that is a different balance, covered in how to fix latency while recording in REAPER.
2. Turn on anticipative FX processing
Anticipative FX lets REAPER render some plugin output ahead of the play cursor instead of exactly in the moment, spreading the work across your CPU cores and smoothing out real-time spikes. Check it in Options, Preferences, Audio, Buffering, and experiment with the render-ahead amount and the multiprocessing options there.
Real-time dropouts happen when work bunches up in one instant. Letting REAPER work ahead evens out the load. A few live or oddly built plugins do not like being processed ahead, so if one causes trouble you can turn media buffering and anticipative FX off for just that track in its Track Performance Options rather than globally.
3. Share heavy FX on a bus
Reverb and other CPU-hungry effects are wasteful when copied onto many tracks. Instead of one reverb per vocal, send several tracks to a single effects track and run one reverb there. You get one instance doing the work of many, which can drop your load sharply. The routing is covered in how to use a vocal bus in REAPER.
4. Freeze or apply FX on the heaviest tracks
When a track is genuinely too heavy to play live, print its processing. Right-click the media items on that track and choose Apply FX to items as new take, or Apply FX to items as new take (Mono) for a mono source. REAPER renders the plugin output into the audio, so it no longer costs real-time CPU. Because it creates a new take, your original take and its FX are preserved, and you can switch back if you need to make a change. This is the most reliable relief on a modest computer.
5. Lower a very high sample rate
If your project runs at 88.2 or 96 kHz or higher, every plugin is doing roughly twice the work of a 44.1 or 48 kHz project. Unless you have a specific reason for the high rate, set it back in File, Project Settings. Most listeners will not hear a difference, and the CPU saving is large.
If REAPER keeps burning CPU when playback is stopped, or a synth tail rings on after you hit stop, go to Options, Preferences, Audio, Playback, disable Run FX when stopped and enable Flush FX on stop. Enter a short tail value, such as 200 ms, so reverbs still fade naturally.
| Symptom | Likely cause | Test | Fix |
|---|---|---|---|
| Stutter and dropouts, meter near 100% | Real-time load too high for the buffer | Watch the Performance Meter during the glitch | Raise buffer, enable anticipative FX |
| One track spikes the meter | A few very heavy plugins on that track | Read per-track load in the meter | Freeze or apply FX to that track |
| Dropouts but the meter looks calm | A single misbehaving plugin | Bypass plugins one at a time | Remove or replace that plugin |
| Heavy load from duplicated reverbs | The same effect copied per track | Count instances of the same plugin | Run one instance on a send bus |
What this will not fix
Lowering CPU load solves live-playback problems. It does not touch these:
- It will not remove clicks or crackle that are baked into a recording. If the noise is in the file itself and plays back the same every time, that is a repair job. See how to fix crackle and clicks in a recording.
- It will not bring back total silence. If you hear nothing at all, that is a device or routing issue, not CPU. See REAPER has no sound.
- It will not turn a slow computer into a fast one. On weak machines, freezing and rendering tracks as you go is the honest answer, not a magic setting.
- It will not remove monitoring latency while recording. That comes from the buffer being set high for live input, which is the opposite trade-off and a separate setting.
- It will not undo work a crash already cost you. If an overload froze REAPER and took your session down, your recorded audio is usually still on disk. See how to recover a lost or crashed REAPER project.
REAPER CPU spikes and stuttering come from real-time load, not your total CPU. Open the Performance Meter to see the real number and the heaviest tracks, then work least-destructive first: raise the buffer, turn on anticipative FX, share heavy effects on a bus, and freeze or apply FX on the worst tracks. Most projects stop glitching before you get to the end of that list.
Sources
- Cockos, REAPER User Guide, Troubleshooting appendix - clicks, pops, stutters and dropouts point to latency too low for the system and CPU-heavy FX; remedies include fewer or shared FX on busses, a lower sample rate, a larger buffer, and the Audio Buffering FX-processing and render-ahead options; “not enough CPU” is diagnosed with the Performance Meter, then fixed with Apply FX to items as new take. reaper.fm/guides
- Cockos, REAPER User Guide (current version 7.78, July 2026) - audio device buffer and block size, the Audio Buffering page for anticipative FX and multiprocessing, and the Performance Meter. reaper.fm/userguide
- Cockos, “ReaPlugs” - the stock FX bundled with REAPER, including CPU-heavier processors such as ReaVerb, which the fixes above manage. reaper.fm/reaplugs