Depending of your computer's configuration or the size and complexity of your 3D files, visualizing objects in VR in Pixyz Review can reach your hardware limits.
For that, we've built an automatic optimization tool which is called "Optimize", available in the toolbar and that will adapt as much as possible your 3D files for AR/VR. If lags are still present, you might have to delete part of the scene to lighten the file or consider using our Pixyz Studio solution to optimize it better.