[Bug 46056] New: u-he Diva: Multicore option slows down performance

https://bugs.winehq.org/show_bug.cgi?id=46056

Bug ID: 46056
           Summary: u-he Diva: Multicore option slows down performance
           Product: Wine
           Version: 3.18
          Hardware: x86-64
                OS: Linux
            Status: UNCONFIRMED
          Severity: minor
          Priority: P2
         Component: -unknown
          Assignee: [e-mail]
          Reporter: [e-mail]
      Distribution: ---

Created attachment 62643
  --> https://bugs.winehq.org/attachment.cgi?id=62643
Edited picture highlighting relevant sections of Diva

u-he's Diva plugin is quite CPU intensive. On Windows, the multicore option on
Diva improves the performance of it a lot. But on Wine, the multicore option
makes it even slower.

You'll need sound output to notice the difference in performance.

You will also need a DAW to test it in. You can either use a Windows DAW (FL
Studio is probably easiest, has a detailed manual and I know it works well in
Wine), or a Linux DAW using LinVST to load the VST plugin (LinVST uses Wine and
requires it to be installed on the system).

(If you decide to load Diva in FL Studio, see this section of the FL Studio
manual on how to scan for and load plugins:
https://www.image-line.com/support/flstudio_online_manual/html/basics_extern...
)

--------

Steps to reproduce:

1. Download and install Diva (link at bottom). Make sure the DAW you're using
has detected it (get it to scan for plugins).
2. Load up Diva. At the lower half of the plugin, the panel just above the
"MAIN" button and below the "tuning" panel, set Accuracy to divine, Voices to
16 and Stack to 4 (see image attached). These settings are to make Diva use a
lot of CPU so that the difference between multicore on and off can be
demonstrated. The multicore button (the button in the top bar to the right)
should be off (i.e. it should be black).
3. In the DAW/VST host, input 4 MIDI notes playing simultaneously into the
DAW/host's piano roll and play them back. Take note of popping and clicking (if
any). If it's popping and clicking then keep in mind how frequent/severe it is.
4. Now go back to Diva and enable multicore (click on the black button). It
should now be red.
5. Play back the notes you input again. It should be even slower than it was
with multicore off.

If somehow one Diva instance with those settings is not enough to cause buffer
underruns (audible pops and clicks) even with multicore enabled, clone the
current Diva instrument (or add a new Diva and give it the same settings as
done in step 2), add MIDI notes as in step 3 but to the new Diva instance and
then play back the notes making sure all the Diva instances are playing at the
same time. In other words, we're trying to layer another Diva's notes on top of
the first one in order to make it use enough CPU to cause buffer underruns.
Remember to enable/disable multicore on both Diva instances when comparing
between the option being on and off. It's unlikely you'll need more than 2
instances at full accuracy settings because this synth uses up a lot of CPU.

Diva has a native Linux version and the multicore option improves performance
as on Windows. But I use FL Studio in Wine and there's currently no way to
run/bridge native Linux VSTs in Windows DAWs (that are running in Wine) so I
have to use the Windows version.

OS: elementary OS 5.0 Juno (based on Ubuntu 18.04)
Tested on Wine 3.19 but I know 3.18 also has the problem.

--------

Download:
https://uhedownloads-heckmannaudiogmb.netdna-ssl.com/releases/Diva_143_7422_...

$ sha1sum Diva_143_7422_Win.zip 
50032d8ed54e22e8ec495d283e02754f2959b665  Diva_143_7422_Win.zip