Particles loading intolerably slowly

I’m having problems loading particles in a specific file. At first I thought it was a general Blender glitch of sorts but now I think it’s related only to one file (for reasons unknown). It’s not a huge number of particles (maybe 20,000 per layer) but the layers with particles load extremely slowly (5-10 mins) despite not using any deflections or force fields. There is one layer on which deflections are used but just one, and it’s not even selected. Also, moving or editing a particle mesh takes much longer than usual (to the point where editing is impractical).

I’ve tried appending the whole shebang into a new file. I did this with both 2.37a and the latest (28/11) CVS build. 2.37 appended very quickly but didn’t solve the problem, whereas the latest version actually worked, but when I closed the file and re-opened it the problems returned. I’ve tried saving as a new file, that didn’t work at all. Opening the file directly with the alpha build doesn’t work. I’m at a complete lost. Interestingly opening with 2.23 DOES work, but that’s not accpetable.

So… does anyone have a clue what the hell is going on ? I would post the .blend but it’s 28 mb, and there’s too many meshes to make it practical to append sections to a new file for saving a smaller version. I can append individual particle emitters easily enough, but they don’t display any problems.

I’m pretty sure as you mentioned elsewhere that it’s a product of the live update added to the new particles. I’ve had the same problems and I have resorted to turning down the Number (used to be "Tot’) before saving.

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I did, but I was wrong. I’ve made test files with many more particles than in the particular .blend without problems - I can move and edit the meshes just fine in realtime, and there’s no loading problems, even after saving, closing and reloading the file.

I’ve done some more testing and I may have found the source of the problem. I went through an older and less complex save file (with less particles and so faster loading times), deleting layers one by one. One layer used duplicates of all the objects in the scene with their materials linked to a black shadeless cube (for use with the warp effect plugin). I deleted everything on that layer and the effect is greatly reduced. Now the particle layer (just the one in this file) loads in under 1 minute, much better than 7. Moving/editing meshes is not quite instant but it’s WAY faster than it was. In fact, in 2.4 alpha is practically IS instant, which is nice.

It doesn’t appear to be a problem with the links between materials - if I remake the layer without linking the duplicates, the problem is still there (in both 2.37a and 2.4 alpha). This make me think it might be a problem with the vertex count - but alas, apparently not. The scene has about 300,000 verticies, double that with duplicates. But I made a simple test scene with massively subdivided cubes totalling 2 million verticies and lots of particle emitters all on the same layer, and still didn’t get the slowdown ! I tried moving the emitters and meshes to different layers - still didn’t get the effect. It appears to be only reproduceable within the affected files, but appending everything into a new file doesn’t solve the problem either.

So, I’m at a completele loss. The only pattern I can see is if I duplicate the meshes in the affected files, the problem appears, and if I delete the duplicates, it dissapears. Unfortunately I need those duplicates and as I edit the file I’ll need to edit them too. I suppose if all else fails, I could ignore the warp effect completely and only put in the duplicates at the very end when everything’s done - but having to do that repeatedly more is added would get annoying.