Remove the „wait .. ticks/seconds“ and which version of Skript are you running?

 

Try this (not tested).

Code (Skript):

1. command /infobook2:
2.         trigger:
3.                 send "&cKommer snart..."
4.  
5. #Indstillinger
6. options:
7.     prefix: &a&lInfo: &c
8.  
9. #GUI setup
10. command /infobook:
11.     executable by: players
12.     trigger:
13.         open chest with 5 row named "&2&l&nInformation" to player
14.         set {_s} to 0
15.         set {Info.%player%.lastused} to now
16.         loop 45 times:
17.             set slot {_s} of player's current inventory to GRAY GLASS named "&c&lIndlæser..." with lore "&c&l&oVent venligst..."
18.             wait 0.03 seconds
19.             ifinventory name of player's current inventory is not "&2&l&nInformation":
20.                 stop
21.             add 1 to {_s}
22.         format slot 21 of player with book named "&c&lIndlæser" to close then run [send "{@prefix} &c&l&oVent venligst..."]
23.         format slot 23 of player with book named "&c&lIndlæser" to close then run [send "{@prefix} &c&l&oVent venligst..."]
24.         format slot 21 of player with paper named "&2&lMap-Byggere" to close then run [execute player command "/MapBuilders"]
25.         format slot 23 of player with paper named "&2&lGenerel &nInformation" to run [execute player command "/GI"]
26.         set {_s} to 0
27.         loop 45 times:
28.             set slot {_s} of player's current inventory to GREEN GLASS named "&f&lIndlæst"
29.             wait 0.03 seconds
30.             add 1 to {_s}
31.             ifinventory name of player's current inventory is not "&2&l&nInformation":
32.                 stop
33.         format slot 21 of player with paper named "&2&lMap-Byggere" to run [execute player command "/MapBuilders"]
34.         format slot 23 of player with paper named "&2&lGenerel &nInformation" to run [execute player command "/GI"]
35.      
36.    
37. on inventory click:
38.     if inventory name of player's current inventory is "&2&l&nInformation":
39.         cancel event