How does the Canon 5d full frame CLASSIC perform in low light situations?

I'm purchasing a used Canon 5d classic and I'm not sure how it will perform in low light. Right now i'm using the Nikon d60 right now and it performs really horribly in low light. Even inside, i really have to push up my ISO to the highest i can (with minimal noise of course) and i have to have a Really slow shutter speed. Really slow. And my f stop is really low. Its really annoying so I want to make sure that the Classic Canon 5d doesn't have the same issue. Please let me know!

Since you already own a Nikon system, there's really no reason to switch to Canon, since the Nikon D800 and D810 (contenders with the Canon 5D series) have some of the highest performance at high ISO.

You may want to visit the link below to see how all the different camera sensors perform.

Most of your annoyance is caused by not understanding the fundamentals of photography.

To reduce noise, you must balance fast lenses with high performing sensors in the available cameras in the system you own at this time.

Of course your shutter speeds are going to be slow if you stop down the lens, this is exactly the way it is. Changing cameras or camera brands will NOT change the fact that with smaller lens apertures, the shutter has to stay open longer. It is part of the reciprocity. Lens aperture vs shutter speed.

Here is a second link that will help you understand how to balance ISO, shutter speed and lens aperture. You will notice that this balance is NOT camera specific, but just one of the fundamentals of photography.

And no, buying a good used 5D is NOT going to solve your problem

If you have to use ISO1600, f/1.8 and 1/5th second on a Nikon D60 then guess what you will be using on a Canon 5D?
Did you guess right?
ISO1600, f/1.8 and 1/5th second

Don't waste your money on a new camera until you understand the one you already have.

Compared to APS-C, I believe full-frame is better in low light but I'm pretty sure it's not as good as you want it to be. If you really want low light shooting power, get a Fujifilm X-Pro 1.