Animated ads can be brutal on older computers. I'm using Chrome to make this post, and it doesn't automatically start animated ads... most of the time. There's a setting for that. It also uses it's own version of Flash, if you need it, but the most recent version of Chrome doesn't activate Flash by default.
I don't like to deprive websites of advertising dollars, but ad blocking software does work.
The Chrome-based Opera browser includes ad blocking software. It also seems to be quicker than Chrome on older computers