Of particular note with Pawz's changes...
Each tier of enemy will split into the next tier down rather than skipping tiers. This goes Behemoth - 2x Titan - 2x Giant - 2x Huge - 3x Big - 3x Medium - 3x Small. In Vanilla, Behemoth splits into 3x Big.
-- More changes that were not put into the Pull Request: --
When more than a certain number of enemies are killed per tick, they are no longer queued. This is deliberate to make atomic bombs an effective option. Extensive testing before this fix proved that all atomic bombs did was give you thousands of angry bugs to tend with. Area of Effect weapons are now far more useful, like Bob's H.E. Bullets.
Attack code has been added to order newly spawned splits to immediately attack whatever killed the parent. This prevents confused kill zones where bugs would spawn without clear direction along your perimeter wall and get cut down before they decided what to do.
With Bob's, a combination of high tier lasers plus flamethrower turrets is an effective alternate to HE bullets. Without the flamers, the laser walls will get overrun in the late game.