You're right. When I use Java webstart 32Bit the aerial is fast. The same with Java webstart 64 Bit is slow. Before I had to give a rule to NVidia to prevent jp2launcher.exe running with dedicated graphics.

"C:\Program Files\Java\jre1.8.0_144\bin\javaws.exe" -J-d64 http://www.sweethome3d.com/SweetHome3D.jnlp
Sweet Home 3D ® Version 5.4
Java Web Start
Java version 1.8.0_144 / 64 bit / 2 GB max
Java 3D version 1.6.0
-> Slow

"C:\Program Files (x86)\Java\jre1.8.0_144\bin\javaws.exe" -J http://www.sweethome3d.com/SweetHome3D.jnlp
Sweet Home 3D ® Version 5.4
Java Web Start
Java version 1.8.0_144 / 32 bit / 0.6 GB max
Java 3D version 1.6.0
-> Fast