Need Help with FFXIV Configuration

[Anima]

So I'm actually not a new player, but I feels weird to post "Config" question in General Discussion so I'm gonna ask here.

I'm playing FFXIV in an average Config, but I'm playing on Limit FPS 30.

On FPS Limit 30, I use:
Multi-sampling: 4xMSAA
General Drawing: 8
Background Drawing: 4
Shadow Detail: High-Highest
Ambient Occlusion: None
Depth of Field: None
Texture Quality: High
Texture Filtering: Highest

AMD Setting:
Anti-aliasing: 4x
Anisotropic Filtering: 8x
Tesselation: 64x
Texture Filtering: Quality
AA Mode: Adaptive MSAA

I have no problems, no lags, all smooth with these config, but once I change Cap to 60 FPS the game Lags when there's a lot of objects to load, and especially on Raining, Sandstorm, CS, etc.

A few questions, What is the difference between 60FPS Cap and 30FPS cap ? Is it beneficial for me to change Cap to 60 whilst lowering some of my configs ?
I want the game to look great/decent while running smooth in all cases >.>
(Searched about FPS but couldn't find any hints, I know that's Its Frames per second / Frame rate)

-Thank you

P.S.
If I'm staying for 30 FPS Cap I can raise my config a little, If It's 60 FPS Cap I've to lower some of my config quite a bit.