Source?
The fuck are you talking about? They literally go feral if they don't have Synapse Creatures.
Don't try to bullshit with made up 40k stuff I literally have the Tyranids codex physical copy at hand
Except you know they left the circuit undefended which is the only reason that was possible.
It literally says their Maiden Planet was consumed, they most definitely lost that battle and it was definitely a loss when it's saying "such a loss was a terrible tragedy"
They do fine against them sometimes, it's 50/50.
Slower is subjective, the Mobile Infantry uses jump packs so they don't physically run as fast (Altho they can briefly outpace an Arachnid running at 35 mph)
but weaker weapons?
Show me Eldar Infantry doing this
So?
The ship warfare has nothing to do with the Arachnids, their role is the ground combat.
The ship warfare goes to the Locusts who can most definitely clap the cheeks of anything short of a Crusade level force.
I wouldn't die on the hill of Eldars who have less than a hundred planets being able to stomp this alliance.
It literally takes them centuries to reproduce