Kaboom might be 95% average speed/faster but Kaboom is not very good unless the target has a generous hit box (number of hits based on enemy hit box size, book Djinn sent me says 12 max if I remember right) Hmmm DM% well it's kind of like Peppita's variant of Mirror Slice and can be quite powerful in Power Dance > Kaboom chain depending but that might make it slower, hmmm.
Peppita's fastest option is actually surprisingly her short O spam (spamming her short O as long as she has the fury/until the enemy is dead) which can even outperform Maria's Scatter Beam spam in specific circumstances/under the right conditions, I think this usually requires at least Increase HP damage though.
Incidentally Peppita's own counters are kind of sort of counter stance counters (at least I've seen some DLrs refer to them as such before) though also in game if she's using a short O and the enemy decides to attack as she goes to use it then her counter animation/counter O will trigger instead.
Though personally I don't know what a Ramsus is, what kind of hit box it has or if it has anything Peppita could counter~
Edit - This topic might help for skill times and such -
http://www.gamefaqs.com/boards/536705-star-ocean-till-the-end-of-time/48222873(chain times and DPS stuff, there's lots of shiny numbers and maths and stuffs~)
(these tests were based on the NA version of the game if I remember right, some skills including Peppita's dances execute faster in EU/UK/etc versions, for example Power Dance cancelling/chaining is pretty much instantaneous in the EU/etc versions >.>)