Sorry, copie la version corta. Aca tenes la explicacion completa si queres xD
One not very known factor regarding skill delays is the effect of your attack speed on it. Your minimum possible skill delay is defined by your attack speed, regardless of what class you are. A lot of people might not know of it, mostly due to it not being on eA until 8? or so months ago, to my knowledge.
The rule is that your delay on a skill cannot be less than half your attack speed. (I'll explain this in a moment.) This includes being under the effects of Magical Strings. If you were to wear a fist type weapon a priest (30-40 ASPD) and attempt to spam Gloria in strings, you'll find that you can't, it will be slow as shit, compared to using a rod.
If your ASPD is 157 you attack every .9 seconds, and half of that is your minimum attack speed.
Example:
High Priest ASPD 157
~1.1 hit per second.
Attack every .9s
Minimum delay = .45s
Lex Aeterna = 3s delay
100 Int Strings = -90% = .3s
This was using ~130 dex and No Agi to base it's ASPD, but it is using a Concentration pot.
Biochemist ASPD 165
~1.4 hits per second
attack every .7
Minimum Delay = .35s
Acid Bomb = 1s delay
100 Int Strings = -90% = .1s
99 dex, and Berserk pot.
I did a series of tests with skills that rely on Magic Strings and found that the only skill capable of utilizing more than 100 int strings (in my test at least) was Storm Gust (which is supposed to have a server-side imposed minimum delay of .75s which seems to be missing on eA), however in game tests that show that the difference between 100 and 120 int is almost unnoticeable due to animation delay.
Long story short: Regardless of your class, using ASPD potions will allow you to use your skills faster under the effect of Magic Strings. Even without Strings, you'll notice a difference with your ability to spam Hide.
If your cast delay is greater than your action time. Increasing your aspd will have very little effect and you will hardly notice. So basically, if you have crappy strings, your aspd won't help you. With good strings however, your aspd will help you spam much faster.