×Breaking walls is unnecessary. There's also a little leeway, since a hint above mentions killing the brain on turn 229, but I hit it on turn 231.
Looking at my demo, I can only note one major trick with the roaches.
How are you dealing with the passage at the bottom of the room?
Click here to view the secret text
×It's actually faster to wait at the two-wide gap at the west side and clear roaches by swinging back and forth. You end up getting a gap that lets you charge through the last roaches there.
If that's not where you're having a problem, I'm not sure I can give any particular advice.