Is there a less consuming program than After Effects?

I'm trying to make a three minute animated music video; however, only about 15 seconds will actually be animated. The rest will be a slideshow of cartoons. I thought it would be fun to create this cartoon with PowerPoint, but it's impossible because PowerPoint cannot handle enough slides. My distant cousin is an animator, and he recommended AfterEffects. A friend of mine who's a filmmaker recommended Reallusion; however, my guess is AfterEffects is more suitable to my purposes considering that only 15 seconds will be animated, and I plan to create that animation by physically moving cut-outs of drawings and scanning them.

I wanted to try the AfterEffects trial, but the program said I did not have enough memory. I asked the IT woman at my work for advice, and she said there was no way my Macbook Pro Retina (Processor: 2.7 GHz Intel Core i5; Memory: 8 GB 1867 MHz DDR3) could handle AfterEffects. She suggested I contact Adobe and ask about other programs.

Does anyone have any suggestions? My cartoon will have music, but a majority of it will just be a slide show of black-n-white cartoons. The only section that will be animated will be 15 seconds of cars in traffic.

Thank you for your help.

Megan