Hi
... index.php is consuming too much server?!
Don't get me wrong, but if it was index.php this problem was way up discussed by other.
You can try optimize your website loading time. On template parameters you will find some options to do so.
Also, Google "test website speed" and you will find some solutions that will provide you a report. For example:
http://websiteoptimization.com/services/analyze/
I don't know who's your host provider and their quality services, so i can't make any judgement (and honestly, it's not my intention), but for me this comes from host side.
Cheers