I cleared the map in 40m... Then the arachnid superwave lagged me out. I gave up at tankers cause lag was 10+ seconds because things happening 10 second after you order it sucks. Lol. Like who is playing the game at that point.
The mission runs a lot better with the off map plasma grenadiers removed.
From 10 minutes on I was perpetually out of dropships. 4 isn't enough to support 100+ supply and 500+ material.
I kept pretty much all allies and civilians alive... Which probably caused a lot of lag. At some point parts of the city should be airlifted out. Call it rearming or something cause we get a TON of reinforcements later.
iirc, this map was made before material was really a thing. Now that it is, we can build 200ish turrets... That's kinda too many. If you had 2 engineer squads building turrets for the entire game, they would never run out of war support. O.o Not necessarily a bad thing.

@Alaska thanks for the information! Definitely will try to decrease the lag!

The lag isn't due to the number of bugs. It's the off map plasma grenadiers. Every single shot is a new 'unit' and stays in the map and is counted as a unit, so every single shot takes more RAM until you crash.
It's a super old bug that really should have been fixed ages ago.
You could probably fix a good chunk of the lag just by removing the neutral plasma grenadiers. Maybe combining a few squads would also work.