rendering speed

is there an option to speed up rendering. like memories allocation or other.
making object dont cast shadow for the floor or tips like that

if your just previewing your animation or image
use HamX file format
it will be readable only in blender as far as i know
turn off antialiasing
turn off AO
if you have dual core or two processors change number of processes to 2
theres more
like shawdow samples
lighting samples and etc…

Yeah, first off, optimize your settings. Use AO only when necessary - you can even fake it with good lighting setups (broken’s work on AO seems to make it quite a bit faster, as far as I know - you might want to check out his patched versions of Blender). Also, anything raytraced will add to the rendertime, like transparency or reflections. Try to keep them at a minimum. Same goes for Anti-Aliasing - keep it at a minimum and use a good filter (box, the default choice, is not always best - check the manual for more infos on that).

These are the standard procedures…it depends on your scene if you can do even more. But as far as Memory allocation goes - I have not yet heard things about that. Of course you can also check out the optimized Blender builds which get better rendertimes on specific hardware.