This is what I find to be the SMOOTHEST endgame [Mesa] build. This build makes your Peacemakers buttery smooth, essentially making them instant (both taking them out and holstering them). This build has allowed me to clear most of the Steel Path solo, and can easily take out most content.

This build is VERY endo and time heavy. If you are a beginner or someone who is just trying out [Mesa] I do not recommend this build. Use this build instead.

MODS

Aura Slot:

You can use anything here, I personally use Energy Siphon or Corrosive Projection.

Exilus Slot:

Streamlined Form - My personal pick. Additional holster speed makes the Peacemakers extra snappy, and the added mobility is useful for traversing missions.

Synth Reflex - If you don't have Streamlined Form, use this. Basically the same mod, without the added mobility.

Other Options - Unfortunately, any other options require either an Umbra Forma or the use of a standard [Vitality]. If you do decide to do this however, you can use Mesa's Waltz, Power Drift or Primed Surefooted depending on your preference.

Mods:

Vigorous Swap - This mod is almost never seen on [Mesa] (or any warframe for that matter) and I think it is really underrated. This actually adds quite a bit of damage and makes holstering your Peacemakers instant. Holstering your Peacemakers then pulling them out again activates the 165% damage buff, and can absolutely shred any enemy.

Other Mods - Everything is fairly standard for [Mesa], lots of duration for [Mesa]'s Shatter Shield (her main source of survivability), efficiency to make it easier to spam your abilities and power strength to increase the damage of your Peacemakers.

Other Options - If you are using this build in an Energy Reduction Sortie, you can replace [Vigorous Swap] with [Primed Flow]. If you just want more energy all the time, I recommend replacing Transient Fortitude with Primed Flow.

Arcanes

Arcane Velocity - By far the best Arcane on Mesa. More than doubles your DPS.

Arcane Energize - Just a good general arcane, allows you to obtain more energy from energy orbs

Arcane Guardian/Grace - Good options for survivability, use these to replace Energize if needed.