Building Light Cache too long & ies not showing in render

[vtchan68]

Need help guys, my light cache is taking too long to build. i know this is a common problem, but i'm new and i need your help for troubleshooting, i got a submission in around 36 hours
My ies light also isn't working too well, the first few ies lights work, but when i'm done placing all ies lights (i made more copies of those lights with the same settings), they just dont show in my render output..

[vtchan68]

here are my settings, i tested out the ies thing, turns out i need to put the intensity higher. but that's not the case, when i test render a few hours ago(before i place the rest of the lights). the interior was much brighter.
For example, the ceiling pattern used to be visible, now it's not..
the "building light cache" phase took 7 hours and it wasn't completed yet. So i tried to change my light cache settings and let it load from a light cache file i created, only then i could render. but what does this mean, does it mean that there's a problem with my ies file?

[andybot]

If you are having trouble with light cache progress, the first thing I would do is make sure you don't have any large areas of displacement. Turn off displacement in all your materials to render your LC pass. You can turn displacement back on for your final render if you save your LC and use it "from file".

[TedVitale_CG]

The next thing that can greatly slow down a renderings LC is the use of transparent diffuse textures. Always turn them into a VRayBRDF glass material and delete your diffuse layer. If they the material is supposed to represent a soft transparent material use a V-Ray two sided material to simulate a soft transparent (cloth, drapes, lamp shades etc..) Your rendering speeds will be greatly increased.