Have you considered having some maps run Katmints Lag reduction script automatically?
This lua script reduces lag from maps significantly by deactivating all objects on spawn and only activating them while they're within a certain radius of any player. Objects activated by proximity will deactive a few seconds after the player...
mb.srb2.org
When I was messing around with Scratch and Grounder last night I realized I'd had it on since the OLDC, and turning it off took my framerate in Lost City from 60 to 6. One or two of my other mods is probably affecting performance, negatively, but that is still a HUGE boost. I'm not 100% sure on the details because I don't have much experience actually making mods or doing more than minor edits, but from what I understand it makes most objects wait until the player is within a certain distance to actually start moving.
I didn't notice any problems that seemed like it could be cause by it until right before I remembered it was running, and even then some enemies not properly existing before a certain distance isn't usually noticable. (It also prevents just straight up sniping Scratch and Grounder, but not shooting from still outside the room.)
It might also help a little bit with
@El3ctr0h3ll's complaints, maybe. "Cycles" is usually a speedrun term referring to objects that start moving at the start of the level, causing you to need to arrive at a specific time for optimal speed and putting a bit of a limit on how fast you can go because you might have to wait. It could also be worse for that, though, cycles are very reliable and something not activating until the player is close enough might be less so, I'm not a speedrunner I just watch GDQ every once in a while. Also, I feel like the motorcycles waiting makes them a little more managable, come to think of it, they
were a bit more of a pain in Royal Palace when I disabled that script.
I feel like the overrall difficulty level is fine, though, especially in the context of Sol Sestancia 1, which I just replayed with Tangle and Whisper. Also congratulations you got my ADHD Hyperfixation hooked on SRB2 again, I think.
Also, very minor nitpick/inconsistency, probably nobody will notice, but the Science Fair in SS1 explains the minerals in the mountain cave at the end of SS2, and you changed what the colors do between releases.
Also I found SS1's Whisper cameo!