Why do WebGL builds take an unreasonable amount of time and resources to complete?

I have a Ryzen 2700x processor, 32GB of RAM, and my Unity project is sitting on a Ramdisk. I have an incredibly powerful workstation that has delivered in every category over the last 2 months for both heavy workstation use and gaming. That came to a screeching halt when I did a WebGL build of my Ludum Dare 43 game this weekend.

My computer takes over 10 minutes to make the build. My 8 core/16 thread processor gets pinned at 100% utilization and the computer is nearly unusable during the entire process.

What in the world is going on during a WebGL build that brings my computer to its knees?

 

It's running IL2CPP, Emscripten, and then packing and compressing your content. Also, the first time you build, it may be compiling shader variants, which can take a while. After the first build it should be a lot faster.

I am curious how much the Ramdisk has helped. Maybe you could benchmark it with/without the ramdisk?

 

I went ahead and ran a mini benchmark for you:

WebGL build on Samsung 860 EVO (SSD): 11m 56s
WebGL build on 8GB CORSAIR Vengeance LPX ramdisk (2800MHz): 11m 22s

That is roughly a ~5% performance gain which I would consider negligible. I think the performance between the two storage options is so similar because the majority of the WebGL build is encoding/compression which would largely be the CPU's responsibility.

 

That sounds about right, There are some settings in emscripten(-O0, -O1) that can significantly improve compile time, but I'm not sure how/where/if they are exposed to Unity.
https://kripken.github.io/emscripten-site/docs/tools_reference/emcc.html

 

I poked around and the build options are quite limited. I would make a thread requesting command line parameters to be supported, but I have never gotten a response from anyone within the Unity organization about anything, so I will save the keystrokes haha.

 

I really dont care how long it takes to do the build, as long as after all that crunching it's small and works!