Funny comparison: by the time I have completely finished loading everything (full world state, all assets) and brought up the game, editor and Live++, UE5 hasn't even brought up its splash screen ;). Still love working on my own tech.
Loading all 1.6GB of current assets (textures & meshes) in 570ms on my 10-year old machine (with a 2080 Ti) using IOCP and unbuffered async reads. Happy for now with this! Final optimization for deployment: loading from a single compressed archive instead of N files.