BlendLuxCore takes an absurdly long time to export whitewater from Flip Fluids and uses only a single thread

It appears that it may be related to https://github.com/LuxCoreRender/BlendLuxCore/issues/197, but I'm not sure. This may also occur with any large object count, such as a render with many very low poly NYC buildings (mostly untextured) which had import times almost as long as it took to actually render each frame.

System Information

Gentoo Linux kernel 4.18.5-gentoo, AMD Radeon RX 480 8GB, 2x Xeon X5560, 4 core 8 threads each resulting in 16 total threads.

Software Version

• Blender version: 2.79b
• LuxCore version: 2.1 beta3
• FLIP Fluids checked out straight from GitHub a couple days ago.

Short description of error

When rendering water generated with Flip Fluids with whitewater on, exporting the particle objects takes many minutes and uses only a single core. Since this is taking almost an hour and I am only actually rendering for around 20 seconds, this performance is absolutely terrible...

Exact steps for others to reproduce the error

Install Flip Fluids (this can be done by compiling from source, zipping the bl_flip_fluids/flip_fluids_addon folder, then installing the zip).

Add a domain.

Add a plane-like cube as a collision object in the domain.

Add a water inflow in the domain.

Check "Enable Whitewater Simulation" and all whitewater particles under "FLIP Fluid Whitewater" in the physics options of the fluid domain.

Click "Bake" (make sure you have lots of space available on your bake disk though!)

Several hundred frames in, when the water has hit the cube-plane and made lots of whitewater, render the frame or even use the preview render. It will take ages just to prepare the scene, orders of magnitude longer than Cycles even opening Blender from scratch.

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The issue provides no file or test entry point. Start by reproducing the Flip Fluids whitewater case using the listed Blender and LuxCore versions, then compare export time and thread usage with the large-object example. Done means the whitewater export no longer takes many minutes or uses only a single thread.