Regular rendering doesn't utilise CPU at 100%, while interactive does.

[Noah45]

Additional information for troubleshooting

The example uploaded will only render between ~68-74% for both regular and interactive.

Some Max files will render all @ 100%, and others vary 

[davood.kharmanzar]

Every -other Max file I open and render does this: CPU utilization, a double digit loss in speed, IR vs. VFB+

More info in post #13

Turn off the "Low priority" option @ render settings ... it may be helped !!

[Noah45]

Was worth a try, and it did seem to average a couple % pts. (75% vs ~72%) thanks

Uploaded a new file for the Corona Team.

1446341553_Test2.7z

[Ondra]

both scenes render here fine. Have you tried unloading the VFB+ and re-rendering, or trying Corona VFB? Alternatively, you can capture a minidump while Corona is rendering (see https://coronarenderer.freshdesk.com/support/solutions/articles/5000524006) and send it to us, we can take a look if something is blocking the computation

[Noah45]

Picked that same project up, and it's cooking along nicely. I'll take a mini dump, if it happens again... : ]

[Ondra]

seems irreproducible

[hrvojezg00]

I have a similar problem, cpu utilization drops to 60ish%. Also using VFB+, will check if native Corona FB renders better. I think it also has something to do with Siger materials.