PIE Client mode starts a server in the background and everything is run under “one process”. This is more performant than a server, and 2 client instances. Disable that and you’ll see what I mean.
The hardware you’re running on is also a huge factor. Servers (listen server hosts) need a lot of CPU and RAM.
Question I have is why are you running network emulation on a packaged build that’s networked over LAN?