AE Problem with rendering

Hey everybody

I have a Question. I'm using a Nikon D800 and my testvideo was shot in 720p with 60 frames/s. I editet it with a twixtor effect, some color correction and brightness/contrast adjustments and then I added a mojo effect and a little blur. Then I rendered it by clicking 'make movie'. At the end of rendering it had a length of 24 sec but the size was about 4GB. Is that possible? And cause of this enormous size, my computer wasn't able to even play the video, means it lagged so hard that it was unwatchable.
My question now. Is this size realistic? If yes, how can I reduce it, without harming the quality?

Thanks for your help
Regards
Frank