Optimize formulas (FUNCTION: LOOKUP) to make an app faster

[daniel_sanchez]

Hi, I created an App to Manage the entrances to mi warehouse, I also with the same app manage the outs. It works in the following way:
We paste the information about each skid the material in a table called " Skid Load Summary" the information contains:
Load Number (the number is not repeated, each skid has a unique load number), trailer number, carrier to pick up, and date to delivery.

 When the trailer arrives at my warehouse, the user scans each pallet, and in the APP shows it to the carrier to pick up (FedEx, UPS, Etc)..

The scans of the entries saved on another table called "escaneo de Skid", for the app shows the information that previously load in table "Skid load Summary" I used the function lookup:

In many processes, to my app, I used the function lookup, and then as more and more data is added it gets slower and slower to do a sync.

the sync times exceed the one minute: 

The question Is: is there a better way to optimize or some other function that does not affect performance so much?