i have an i-7 mac with 16gb but ae still slow?!

[Todd Kopriva]

See “Improve performance for a long list of things that you can do to speed things up.

See these two posts on my blog for advice on optimum settings for memory and processor usage:
“Performance tip: Don’t overschedule your processors.”
“Performance tip: Don’t starve your software of RAM”

> when i select multiple processing it seems to slow things down rather than speed up

from the “Render Mutliple Frames Simultaneously” section of After Effects Help:
“Using the Render Multiple Frames Simultaneously multiprocessing feature does not speed up the rendering of all compositions. The rendering of some compositions is memory-intensive, such as when you are working with very large background plates that are several thousands of pixels tall and wide. The rendering of some compositions is bandwidth-intensive (I/O-intensive), such as when you are working with many source files, especially if they are not served by a fast, local, dedicated disk drive. The Render Multiple Frames Simultaneously multiprocessing feature works best at improving performance when the resource that is most exercised by the composition is CPU processing power, such as when applying a processor-intensive effect like a glow or blur.”

———————————————————————————————————
Todd Kopriva, Adobe Systems Incorporated
putting the ‘T’ back in ‘RTFM’ : After Effects Help on the Web
———————————————————————————————————
If a page of After Effects Help answers your question, please consider rating it. If you have a tip, technique, or link to share—or if there is something that you’d like to see added or improved—please leave a comment.