Hello Pascal,
I think I have - I have to use 32 bit Rhino 5 it if I need to use the Pointools plugin (which is for Rhino 4 and so is only 32 bit - it deals with large pointclouds), but I’ve not used that plugin for a few months as I’ve moved to the newer Arena4D plugin, which works with the 64 bit version.
Recently I’ve only used the 32 bit version for about 15 minutes at a time, so I’ve not had the slowdown problem.
Jonnie