Hitfilm 4 express slow export
I've been editing a project for about 2 weeks now. I was doing some rendering tests before and it took about half an hour to render the 8 minutes long clip. But now when I am render the final clip(12 minutes long), it tells me that the remaining time is 1.5 hour and it crashes at about 15 minutes before completion. The estimated remaining time increases too and hardly ever lower. So it takes a long long time and can't even complete before it crashes. I have not updated any drivers of the GPU since the start of this project. Is there any ways I can resolve this problem?
Intel I7 4790 @3.6Ghz
Geforce GT 720 @ 200Mhz overclock
4TB external HDD
Windows 10 Home 64bit