Faster Notes Guide
There are 4 main methods for playing faster notes. All involve modification of some sort.
Terraria Item Modifier is a patch that adds advanced item customization capabilities to Terraria through configuring an XML file. Modify almost any item variable by editing the ItemModifications.xml file in your Terraria folder. A preset for fast instrument playing is included in the Example XML page.
Pros: Well documented | Vanilla or Modded | Should work with TerrariaPatcher
Cons: Requires XML | Requires looking up IDs | Not a TerrariaPatcher plugin
TerrariaPatcher is a program that modifies your Terraria executable in order add a variety of quality of life features and cheats. TerrariaPatcher comes with a selection of plugins that you can enable. The plugin needed to decrease use time is ItemConfig. With this you can modify a config file to change settings for items in the game. This may seem like a good method but based on experience, this plugin causes horrible lag that makes the game unplayable, let alone in a state to play midis.
Pros: Vanilla or Modded
Cons: Unplayable amounts of lag | Requires looking up IDs
This has not been looked into yet so there is no information on if a mod to do this exists or not. It shouldn't be too difficult to make one though.
Pros: Easy to use
Cons: Mod needs to be maintained | Not vanilla
CheatEngine modifies the memory of a program allowing changes to items and gameplay. CheatEngine gets the best results out of the 3 options listed here however there is no guarantee for the safety of the user with this program. The dev packs the installer with potentially unwanted programs (PUPs) and has even come out and called anyone who uses the installer version an idiot. There is a standalone version that seems to not have any of that garbage packaged in but there's no guarantee. CheatEngine is what was used to record the Terraria Midi Player preview videos.
Pros: Best results | Vanilla
Cons: Shady | Complicated to use