It's not that slow.
Use the flowchart on GameFAQs once you've seen two or three different endings. Puzzling the paths out by yourself is not impossible, but it will be tedious. Also, report back with your first ending, provided you play that far. spoiler (click to show/hide)
My first was the axe murder. Jarring.
Check the plates for a hint. spoiler (click to show/hide)
Hexadecimal.