# What make lightning build slow or fast ? CPU or VGA **URL:** \ **Category:** Rendering\ **Tags:** unreal-engine\ **Created:** [November 15, 2016, 2:02pm UTC](https://forums.unrealengine.com/t/what-make-lightning-build-slow-or-fast-cpu-or-vga/376355 "2016-11-15T14:02:20Z")\ **Posts on this page:** 6\ **Page:** 1
**Author:** ![anonymous\_user\_24b63bb4](https://d3kjluh73b9h9o.cloudfront.net/original/4X/2/8/5/28502927f1d97ba1051b3b47ccfe17233bf41ef0.png) [@anonymous\_user\_24b63bb4](https://forums.unrealengine.com/u/anonymous_user_24b63bb4)\ **Post date:** [November 15, 2016, 2:02pm UTC](https://forums.unrealengine.com/t/what-make-lightning-build-slow-or-fast-cpu-or-vga/376355/1 "2016-11-15T14:02:20Z")
Hi everyone, As my question about building lighting. With my case below, is it eoungh for architectural scenes and interior scenes ? Thanks. Here is my case: Intel Xeon Haswell 22nm E3-1230V3 ASRock Fatal1ty H87 Performance LGA 1150 Intel H87 HDMI SATA 6Gb/s USB 3.0 ATX Intel Motherboard 16GB DDR3 1600 120GB SATA3 6Gb/s Quadro k620 Consair CS750M - 80 PLUS GOLD ---
**Author:** ![housekiller](https://d3kjluh73b9h9o.cloudfront.net/original/4X/2/8/5/28502927f1d97ba1051b3b47ccfe17233bf41ef0.png) [@housekiller](https://forums.unrealengine.com/u/housekiller)\ **Post date:** [November 15, 2016, 3:06pm UTC](https://forums.unrealengine.com/t/what-make-lightning-build-slow-or-fast-cpu-or-vga/376355/2 "2016-11-15T15:06:07Z")
That depends on the scene. Some small scenes with very simple lighting I can build with less than 16GB RAM. Huge scenes that have a ton of lights and geometry will take +200GB Ram (I have 64 and the rest goes to pagefile). To work regularly with heavy scenes you might want to look at a better CPU and more RAM. As long as you provide enough room for a big pagefile you could get a lot done with your system though, it just won’t be as fast as a 6/8/10 core i7 with 32-64GB ram of course. You should however get a better impression of the complexity of the scenes you want to work with so you’ll have a much better idea of what you actually need. For real time visualisations your GPU should be the first upgrade to consider. ---
**Author:** ![Luos](https://d1ap1mz92jnks1.cloudfront.net/user_avatar/forums.unrealengine.com/luos/32/918700_2.png) [@Luos](https://forums.unrealengine.com/u/Luos)\ **Post date:** [November 15, 2016, 3:46pm UTC](https://forums.unrealengine.com/t/what-make-lightning-build-slow-or-fast-cpu-or-vga/376355/3 "2016-11-15T15:46:16Z")
To add to Housekillers answer. Building lighting is entirely CPU, not gpu. So CPU and RAM are the most important for building lighting. IT also depends on the amount of meshes and their lightmaps how long rebuilding light will take. a mesh with a 1024 pixel lightmap will take waaaaaaaaay longer to be lightmapped than a mesh with a 32 pixel light map. ---
**Author:** ![Tim\_Hobson](https://d3kjluh73b9h9o.cloudfront.net/original/4X/2/8/5/28502927f1d97ba1051b3b47ccfe17233bf41ef0.png) [@Tim\_Hobson](https://forums.unrealengine.com/u/Tim_Hobson)\ **Post date:** [November 16, 2016, 9:53pm UTC](https://forums.unrealengine.com/t/what-make-lightning-build-slow-or-fast-cpu-or-vga/376355/4 "2016-11-16T21:53:37Z")
In addition to the suggestions here use the Statistics Window to see what meshes are taking the longest to build for the scene. This can help you narrow down and optimize these that are taking longer. > **[A new, community-hosted Unreal Engine Wiki](https://forums.unrealengine.com/t/a-new-community-hosted-unreal-engine-wiki/141494)** > > After over a year in maintenance mode, the official Unreal Engine Wiki is now permanently offline. These resources now live on a new community-run Unreal Engine Community Wiki — https://unrealcommunity.wiki/! You will be able to find content from... ---
**Author:** ![anonymous\_user\_24b63bb4](https://d3kjluh73b9h9o.cloudfront.net/original/4X/2/8/5/28502927f1d97ba1051b3b47ccfe17233bf41ef0.png) [@anonymous\_user\_24b63bb4](https://forums.unrealengine.com/u/anonymous_user_24b63bb4)\ **Post date:** [November 18, 2016, 2:13pm UTC](https://forums.unrealengine.com/t/what-make-lightning-build-slow-or-fast-cpu-or-vga/376355/5 "2016-11-18T14:13:15Z")
Many thanks ---
**Author:** ![anonymous\_user\_24b63bb4](https://d3kjluh73b9h9o.cloudfront.net/original/4X/2/8/5/28502927f1d97ba1051b3b47ccfe17233bf41ef0.png) [@anonymous\_user\_24b63bb4](https://forums.unrealengine.com/u/anonymous_user_24b63bb4)\ **Post date:** [November 18, 2016, 2:14pm UTC](https://forums.unrealengine.com/t/what-make-lightning-build-slow-or-fast-cpu-or-vga/376355/6 "2016-11-18T14:14:23Z")
Thanks Luos and Tim Hobson,