After reading about Firefox latest news message that they have pumped up the performance (compiling while still downloading) on their webassembly I wanted to see how big the difference was for the standard mobile/scalable project with starterscontent.
The difference is that this project of around 90MiB-100MiB will compile and work almost 3 times faster on Firefox than on Chrome (all last versions). With the same set-up Firefox took 04.460 seconds to start up the project. Chrome took 12.320 seconds to do the same.
My video editting skills are… limited to say but if you want to see the comparison, here you go: Unreal Engine 4.18 Firefox Versus Chrome performance test - YouTube
So at the moment of speaking, Firefox is the clear winner!