If multiple characters use the Perform action, they sync up and play together. Also nearby bards, such as in the Circus of the Last Days, can join the performance.
Nearby NPCs gather to hear the performance and focus their attention on the performer(s). This can create an opportunity for pickpocketing and thievery. Many patrolling NPCs cannot be distracted this way.
If the performer has musical instrument proficiency, they make a Performance check. If successful, the gathered audience tips the performer with Toss a Coin when the performance ends. However, a successful performance does not necessarily result in every attendee tipping the performer(s).
The Difficulty Class of the performance check scales with the size of the audience:
1 audience member: DC 10
2-3 audience members: DC 12
4-5 audience members: DC 15
6-7 audience members: DC 18
8+ audience members: DC 20
Any character can use the Perform action with an instrument equipped. However, a character without instrument proficiency makes a Poor Performance when doing so. This provokes annoyed reactions from the audience who will leave immediately.
Perform is a free action, and can be used during battle. The performance ends if the performing character is Threatened.
Perform '(Bard Dance)' is a free action that allows the user to play the song 'Bard Dance' using their equipped Instrument.
UIDs
Spell flags
Range: Self
check. If successful, the gathered audience tips the performer with 
when the performance ends. However, a successful performance does not necessarily result in every attendee tipping the performer(s).
when doing so. This provokes annoyed reactions from the audience who will leave immediately.
.