Is Twinmotion 2023 handling trees differently to 2022?

We are working in Geospatial visualisation and have part of our workflow involves utilising thousands of tree assets in one Twinmotion scene. We do this by importing an FBX file containing the tree instances (can be up to 40,000) - they are billboards used a placeholders so that Twinmotion can be used to replace them all with much better looking trees from the Twinmotion asset library.

Whilst this process works absolutely fine in both Twinmotion 2022.1 and 2023.1, we have noticed considerable differences in load times between the two when it comes to reloading the scene after closing Twinmotion and reopening. A scene containing 40,000 Twinmotion trees loads in approximately 20secs in Twinmotion 2022.1, but the exact same scene takes upwards of an hour in 2023.1.

Does anyone know why this might be? And, more importantly, does anyone know of a workaround? We have rolled back to using 2022 for now, but this workaround will obviously expire in time.

Thanks in advance for any help!