Why does blender 2.46 lag?

when i use particles or make a good weapon or when rendering animation or image it lags a lot
need help please.

First this is not a support forum. Ask your question there and you’ll get more help and better disposed moderators.

Also make an effort when you ask a question to imagine that you are the one reading it and trying to find an answer. What information would you need? We don’t know what particle system or what kind of sword you modeled, what material and rendering options you used, what kind of machine you have and how long it took to render. The render times depend on the complexity of the scene. Some of the worse culprits : High subsurf values, raytracing, high OSA, SSS, blurred reflections and transparencies, high sample AO, high samples in area lights…