Logic Pro lags when editing many Flex-enabled audio regions

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Level 1

4 points

Logic Pro lags when editing many Flex-enabled audio regions

Hi everyone.

I’m having a serious performance issue in Logic Pro when editing a large number of audio regions with Flex enabled.

The problem:

When Flex is enabled on an audio track, especially in Polyphonic mode, selecting or moving many audio regions becomes very laggy. Even simple selection actions in the Tracks area start to stutter heavily. The audio files themselves are not complex, but the project contains a lot of edited audio regions/slices.

What I noticed:

- The lag happens mainly when Flex is enabled.

- Polyphonic Flex mode makes it much worse.

- Selecting many audio regions becomes slow and unresponsive.

- Turning Flex off improves the editing responsiveness.

- This makes detailed vocal/audio editing very difficult in large projects.

My question:

Is there a recommended workflow to avoid this lag while still using Flex?

For example:

- Should I bounce/freeze/flex-render tracks after editing?

- Is Polyphonic Flex known to cause UI lag with many audio regions?

- Are there project settings that improve this?

- Is this expected behavior or a bug?

I’m considering moving some editing work to Reaper because the lag makes large audio edits very slow, but I would prefer to keep working in Logic if there is a proper fix or workflow.

Any advice from Logic users or Apple engineers would be appreciated.

MacBook Pro 14″, macOS 26.5

Posted on Jul 23, 2026 10:46 AM

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Answer 1

yoyoBen

Level 4

3,641 points

Jul 23, 2026 2:15 PM in response to white143

My question:

Is there a recommended workflow to avoid this lag while still using Flex?

For example:

- Should I bounce/freeze/flex-render tracks after editing?

Yes, bouncing/freezing is recommended as soon as your edits are done. With freezing tracks, you can easily switch back to the old edit, if you wish. I personally prefer bouncing but I keep the old projects just in case I have to go back.

- Is Polyphonic Flex known to cause UI lag with many audio regions?

I don't know. I don't choose the Flex algorithms because of their cpu load but because of their musical results.

- Are there project settings that improve this?

Increase I/O buffer size. It will lower cpu load but introduce more latency. Make sure your hard drives have enough free space to work on. Close other applications you don't need. Just a try: Select an empty track with no plugin and input assigned and press play. More info here Avoid system overloads in Logic Pro for Mac - Apple Support

- Is this expected behavior or a bug?

Flex time as any pitch- and time-related actions are cpu heavy. I don't know your computer...

I’m considering moving some editing work to Reaper because the lag makes large audio edits very slow, but I would prefer to keep working in Logic if there is a proper fix or workflow.

Use the software that's suits you the best. Many people (including myself) are using more than one software. No software is perfect.

Any advice from Logic users or Apple engineers would be appreciated.

This is just a user forum.

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