I'm just getting it to speedrunning the 100% category and was wondering what the best settings are. I was also wondering what settings are allowed to be changed in the start menu.

Settings are allowed to be changed on the start menu, however you do not have access to the full menu before starting a file. On a NG+ file, all settings are carried over to the new file so don't worry about changes if you have all these correct already, and your personal preferences correct. If running on a totally fresh file, follow this. Settings are generally down to personal preference, but there are some changes which do simply result in time save:

Before file start:

QTE Auto Complete - ON

After file start

JJJ Podcast - OFF

Danika Podcast - ON

(BUNNY HOPPING ONLY) Re-map either shortcut 1 or shortcut 2 to Air Launcher / Swing Kick

Why leave Danika's podcast on? If turning off JJJ's is a time save, wouldn't the same be true for Danika's?