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 ...

New beta 5.5 b11 is still slow using Intel HD 4000 graphics with Windows 10 up-to-date. Also startup without a project is extremely slow, because of aerial view is starting (first black screen then gray).
Using powerful graphics NVidia NVE4000 (1GB Graph-RAM): Fast.

Version 5.5 Beta 11
Java ...

I could confirm that with Windows 10 newest pachtes, SH3D with built-in Intel HD 4000 graphics (Core i7 mobile QuadCore) is very slow suddenly (at least aeral view). Some months ago aerial was fast enought. Reinstalling Java does not speed up. But I configured the graphics software to use NVidia NVS ...