View Issue Details
| ID | Project | Category | View Status | Date Submitted | Last Update |
|---|---|---|---|---|---|
| 0010450 | ardour | bugs | public | 2026-07-27 15:52 | 2026-07-27 16:37 |
| Reporter | lina | Assigned To | |||
| Priority | normal | Severity | minor | Reproducibility | always |
| Status | new | Resolution | open | ||
| Platform | Apple Macintosh | OS | MacOS | OS Version | 10.12 or later |
| Product Version | 9.7 | ||||
| Summary | 0010450: Mixer/meter drawing is very CPU-intensive | ||||
| Description | Switching to the mixer view during playback with a large (near full screen) window size causes rendering performance to drop and CPU usage jumps from 0000071:0000060% to 0000102:0000120%. The performance loss depends on the number of visible tracks. There seems to be some kind of non-linear scaling, since turning on a couple tracks doesn't make much difference but after adding a few more, the delta for making a new track visible starts becoming higher (e.g. toggling one track adds 10% CPU cost). In addition, toggling track visibility on and off while playback is running itself lags a lot, by over one second when toggling the last track (when it's only a few tracks visible it's fine. This project has 15 tracks, so nothing excessive. Opening the Meterbridge window alone also causes CPU usage to spike. The cost seems proportional to the window height. This makes me think the (or at least one) bottleneck is drawing meters. Changing meter settings, such as toggling LED style on/off or changing the peak hold time from long to off, *briefly* triggers increased performance but it quickly slows down again. That sounds like there is some kind of pathological code somewhere, like a length-limited meter history array or something like that which is repeatedly scanned while drawing the meters, slowing everything down over a brief period of time proportional to meter height. Hardware: Apple M2 Max (macOS 26.5.2) Display: 4K display configured to 2560 x 1440 scaling | ||||
| Tags | No tags attached. | ||||
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I've uploaded a screen recording of the issue here: https://cloud.hoshinolina.net/s/e2esftArWJziarr You can look at the timecode at the top to see the rough refresh rate. In the editor, it's 60FPS without issue. In the mixer, it drops significantly. Simply moving the mouse over the tracks makes it drop even more, to 12-15 FPS. Clicking on another track causes a momentary stutter, and then moving the mouse over the tracks again the frame rate is lower, 10-12 FPS. Switching to the editor view and back brings back the 12-15 FPS performance while moving the mouse. I didn't show meterbridge, but meterbridge + mixer view is extremely slow, easily 6 FPS or less. There's definitely something pathological going on here, and it's not even consistent for a given UI state (there is some kind of memory/state involved). It might be more than one problem combined. |
