[SIgor]

I constantly getting freezes with Cinema when changing Displacement Map to "On The Fly"...

[JDHill]

It depends what you mean by freeze. If the CPU is busy during the "freeze" and eventually the render starts, then it might appear to come down to displacement settings. If it freezes and CPU activity drops to zero, and then remains that way indefinitely, it could indicate some bug in the render engine, or some other problem. If you upload a file (a Cinema file, with related MXMs & textures, to dropbox or similar) that can be used to reproduce the behavior, then a more precise diagnosis can be made.