GUI and computer keyboard input lag when a particular vst tooltip is displayed

While the tooltip for the operator envelopes of Tracktion’s f.'em vst is displayed in Renoise, Renoise’s gui stops updating smoothly and its computer keyboard’s note input lags.

There is no apparent increase in consumption of hardware resources. The issue occurs immediately on moving the cursor to where the tooltip would be displayed, and ends immediately on removing it.

This occurs on 3.2.2 x64 on Windows 10.

Steps to reproduce:

  1. Launch Renoise.
  2. Set an instrument to use Tracktion’s f’em vst as a plugin.
  3. Enable Renoise’s oscilloscope.
  4. Notice that playing notes with the computer keyboard occurs without latency and the oscilloscope updates smoothly.
  5. Mouse over an f’em operator envelope so the tooltip appears.
  6. Notice that keyboard note input immediately lags and the oscilloscope no longer updates smoothly.
  7. Move the mouse away from the operator envelop so the tooltip disappears.
  8. Notice that the keyboard note input immediately stops lagging and the oscilloscope updates smoothly again.

The linked video demonstrates the issue with a pattern being played.

I’m going to speculate a bit… For some reason the renoise GUI stops when some VST / VSTi window is in the foreground and drag. This seems to be programmed like this on purpose to avoid graphical performance issues I guess. In this case, the window is in the background but you cannot escape these problems.

There are also drastic GUI performance issues with 32bit plugins with the current version of Renoise. Something happens with the extra windows that are taken from Windows as frames to display the content (included the popups). A complete reprogramming with the GUI deal would probably be needed to fix these things, who knows. But it seems that all these issues are related, have a single cause, and it is not the VSTi in particular, since they are common issues, that seem to point to windows of Windows O.S…

If it is necessary to invest time to fix things, this should be the first on the list!