HELP: Premiere Pro CC not using all CPU and RAM during rendering and export

Hello,

I am using Premiere Pro CC on a Windows 7. My timeline is quite simple with two videos, one with the movie (mpeg) and the other with the subtitles (avi).

When I render the sequence in PP or export, the rendering time is way too slow and it only uses around 15-20% of the CPU and 3 GB of RAM.

My hardware config is :

- CPU : i7-4770k 3.50Ghz

- RAM : 8 GB

- Disk : 2 x 3 TB SATA (no raid)

RAM is not the bottleneck, neither the disk access.

I have tried rendering and exporting the same project on an iMac (with an i5 2.7 Ghz and 4 GB RAM and only 1 disk) and the result is 4x faster !!!

The CPU usage is close to 100% as well as RAM usage.

So how come PP uses all resources availble on an iMac and not on a Windows 7 ?

Is there any known bug or software bottleneck on Windows 7 ?

My machine is brand new and nothing much installed besides Adobe products.

Any help is very much appreciated.

Thanks,