Blend file size is huge After adding image as planes and use as a particle, size of File and used by ram is increased from 35MB to 568MB.

Ram used 350MB to 10GB

Even if i add ivy file size is 35MB.

Only 3 textures are used (5MB).
Your computer needs to save every single particle position, rotation, scale, physics, etc. in order to properly display them. For a single particle, this isn't much- but it adds up, especially with thousands of them.