First of all, I would like to point out that I am presenting this from a position where I have, at many points in my adult life, been paid in a professional capacity for performance. The current Performance skill is a simplified mechanic which is currently insufficient, in my opinion, to model the actual use of the skill in the real world, let alone at the legendary scale provided by the PFRPG ruleset. I will attempt, however, to not base my argument on authority, because I feel it stands well independantly.
The current performance rules only model the most basic of performance interactions, the busk. For those who are not familiar with the term, busking is when you stand on a street corner, perform, and hope people put some change in your hat. While this is certainly a portion of what performance is about, I think the mechanical effects of basic performance, even when not enhanced by bardic talent, should be able to do more.
First, I think Performance should allow for an intersection with community size. Although community size rules, from the DMG, are not OGL, I would like a DC for Perform scaled to the size of community you are trying to busk and influence. Busking a village sized portion of a metropolis nets you a bonus to Diplomacy of +2, +1 for every 5 you exceeded the DC of the community size for members of that community, and a reward based on the community size + whatever for every +5 over the amount you exceeded the DC. Busking the entire metropolis should have a very high DC of 45 to 50 or more, and a corresponding reward in money. This would be the equivalent of performing for a Emperor and his entire court and retainers, and should be very difficult to get them to fork over cash and treat you with respect.
Ergo:
Busk a Hamlet: DC 10 3d6 sp + 1d6 sp per +5
Busk a Village: DC 15 1d4 gp + 2d6 sp per +5
etc.
Diplomacy bonuses would extend to every member of that community, and a successful Perform check should be able carry a Diplomacy rider, to enable the perform to influence attitude through the performance. I do not think that Intimidate is appropriate as a mechanical rider to a perform check, even if the performance is some kind of martial demonstration, as I feel the context and use of perform is not appropriate for that.
Metropolii, by their very nature, have various neighborhoods, so to busk the Docks, or the Noble District, you would need to only beat the DC to busk a village or town, rather than performing well enough to gain a bonus with everybody in the city.
Bonuses should be able to be gained through tools, like mastercrafted compositions, and instruments, and Aid Another checks should be common and necessary to reach the upper DCs.