Why is rendering raking so long?

Why is rending 7 image and a video taking so long? I've been working on this video for a couple of weeks now and normally rendering something like this would take a minute. In fact the entire project in green took about 2 minutes maybe 4 I don't know.

Now today literally the next day editing it's taking a long time and my GPU is going crazy yet it seems like it's hardly being used on the metrics on screen.

I don't really know what I'm talking about but if anybody know what could be going on?

I had it on a hard drive that was plugged into a USB but not powered up and it was running really slow and so I realized the power plug fell out and I plugged it back in and reset the computer but it's still slow I don't know if I messed something up by doing that

Any help would be greatly appreciated... I also have a 126 gigs of RAM and an updated processor I can't remember off the top of my head but my computer as a whole shouldn't be the issue but maybe it's the hard drive or something I don't know