I do not know if these are the absolute best choices for Episode 5 but I'm pretty sure most of them are and pretty good ones too.

Episode 3: You'll want to be mean to Stella in the lever part so that she doesn't want to be your friend towards the end of Episode 5, the scene of her wanting to be your friend is slower than the scene where she is saying that you are her enemy and walking off and can save a lot of time.

Episode 4: DEFINITELY give Xara her bed, the scene of her getting choked to death is way slower than the scene of Romeo simply destroying Champion City instead. Not only do you lose time from that scene but Chapter 1 goes by much slower if you're talking about how she is approaching the admin and in the map shop they even stop for extra dialogue if Xara dies.

Episode 5 Choices:

Should you either tell Jack to play it cool or be himself?

(It doesn't really seem to matter but might as well:)

b. Tell Jack to be himself

Should you keep Nelli's statue the admin's way or change it back?

a. Keep it that way; you'll have to take extra time to mine out the admin's build that covers yours up and the scene of Nelli getting in trouble is slower

How do you confront the Admin in his tower?

b. Reason with the admin; you'll have a much longer cutscene of the Ocelots fighting if you don't

Do you leave Romeo behind or take him with you?

b. Say your goodbyes to him; you'll lose some time if you have a talk with him after escaping the portal, just go straight to Lukas after your escape (Yes, sadly I don't like it either, I usually take him with instead but I guess someone's life just for a couple of minutes to save is worth it?)

Do you go with Petra or Stay in Beacontown?

ab. Either way, both cutscenes seem to be equal and either ending is eligible for a valid speedrun.

If there is anything that should be added to this guide or fixed let me know. Hope you enjoyed.