Dear Felipe
Thank you for using I-Simpa and for your comments. We appreciate.
Concerning the Time step for the SPPS simulation, you are right, it should not change the reverberation time as soon as the value is small enough (10ms or less should be a good value). What is your value ? What is the size of your room ?
Concerning the second point, this issue is known for the latest version, for some computer. It needs to rewrite the 3D view.
Best regards
J. Picaut