Low Framerate streaming transforms through PlusServer with NDI Lyra tracker

[DamPuls]

Hello

My project is to track Telemed ultrasound using a recently purchased NDI Polaris Lyra tracker.

So far PlusServer connects well with Telemed and the tracker, Images are moving in my Slicer scene. But the refreshment rate is very low (3 - 4 Hz) compared to Lyra acquisition rate (10 - 120 Hz).

My config is Windows 11 / Slicer 5.6.2 / PlusApp-2.8.0.20191105-Telemed-Win32

Firmware of the Lyra is 008.010.017

What I’ve tried to speed up refreshment rate :

Set up only Telemed in config XML : images refresh at 30 Hz- 40 Hz indicating NDI cause the latency

Set up only NDI Lyra in config XML with 4 tools (passive) transforms : rate decrease to 3 Hz in Slicer

Set up only 1 tool in config XML : same

Tried PlusApp-2.9.0.20251125-Telemed-Win64 : same

My last config file looks like this :

<Device
  Id="TrackerDevice"
  Type="NDITracker"
  NetworkHostname="PB-00525.local"
  ToolReferenceFrame="Tracker" 
  AcquisitionRate="60"
  TrackingFrequencyNumber="0">
  <DataSources>
	<DataSource Type="Tool" Id="Reference" RomFile="PHToolDefinitions/Reference.rom"/>
  </DataSources>
  <OutputChannels>
    <OutputChannel Id="TrackerStream" >
	  <DataSource Id="Reference"/>
    </OutputChannel>
  </OutputChannels>
</Device>
</DataCollection>

I’ve played with Parameters like AcquisitionRate , TrackingFrequencyNumber , MaxNumberOfIgtlMessagesToSend , SendValidTransformsOnly but still same result in Slicer.

Reading this post : #1110 , I have checked that the camera does not average frames (NDI is configured with Data Averaging Depth set to 1)

Any hints ?

Thanks a lot !