Yet another stab at optimizing Fun 11, now down to 1689F I believe.
This time I didn't scroll all the way to the right (since scrolling almost guarantees a lag frame each time the screen position shifts), just enough to hide the first explosion. I avoided the second explosion altogether as it seems to add too many lag frames at that screen position, going back to the digger yet again.
Through testing, I've found that the precise x-position of where the digger starts digging can apparently have an effect on how many lag frames it may contribute while digging. Specifically, at the position seen in the movie, or it seems other x-positions offset from that point by multiples of 4 pixels, the digger seems able to dig without generating much lag frames beyond one or two shortly after the skill assignment, while other positions seem to fare worse. Indeed, one variant I've tried simply has him start digging 4 pixels left of where he digs in the attached movie. Doing that avoids the business with the builder and seems to work just as well in avoiding the digger-induced lag frames, but it also somehow wound up adding some lag frames during the fade-out, and so ended up not as optimal as the attached movie.
It does suggest more generally that the lag frame phenomenon from certain skill usages may potentially be minimized by tweaking the exact position of the lemming, if feasible.
I'm also wondering now whether an explosion-free approach in this level may wound up completely eliminating the need to scroll, and thus further reduce the associated lag frames? (Though it may become very difficult if not impossible to achieve the precise timing for doing the sliding glitch, if that lemming also has to free the blocker.)