Questioning the design of TP

[Shaiandra]

Yes, but if the mob was going to die anyways, it's going to die faster for the same TP amount. If x mob takes 3000 TP per kill, then Skill Speed will only let you spend that 3000 faster.

That might be accurate if you were the only one DPSing the mob. If you consume TP 10% faster with upgrades, that doesn't mean the enemy will die 10% faster (assuming the rest of the group's DPS hasn't increased by 10% as well).

If your TP consumption exceeds your total available TP, you run out of TP and your DPS suffers. I don't know the current slopes of TP consumption vs available TP, but if more skill speed increases the former such that TP consumed and available TP now intersect earlier and before the battle is over, well, Paeon becomes a larger DPS increase.