Why are you doing the animation using adobe after effects ?
The flash based animations will be only visible in laptops and computers which support flash and will not be able to load on slow devices as well as hand held devices like mobiles and tabs.
Exactly.Much slower,can crash google chrome engine and graphics will be rendered properly only on a network with good bandwidth.Also,not sure if they're mobile compatible.
I would advise you to get the animation dome in some way that it can be accessed in any design as well it is responsive.
Which is HTML5/CSS3 based animations,faster than flash and responsive.They could use JavaScript based libraries such as velocity.js or d3.js for advanced graphics.