The Particles pack with near 700 sprites are uploaded.
Use the sprites with the black background, they are to mean to be used with "additive". In other way like some smoke, stars,etc... they come in transparent .pngs.
About the slowdown on the laptop, be sure you are using the main GPU and not the motherboard one, we had the similar issue with other guy. Don't know how he fixed, but take a look if the GPU is working a 99% and which one is in case of have more than one.
The curves on timeline i think is a bug XD