Snails pace rendering

ok so ive been messing about doing a few liquid sims and stuff, when i bake or render it takes ages, fair enough i thought that was normal, but then i downloaded a fiery comet blend, and it rendered better than anything ive done in seconds.

this is probably in the wrong section but how is my stuff rendering so slow compared to the other blend, some kinda settings or process im not using?:no:

There are a huge number of factors that can affect the speed of rendering. Add a link to your blend file so others can see what you have and maybe give some recommendations on speeding things up.