Optimize comparing two datatables

Hello Uipath family,
Currently, I am trying to find the best way to compare two columns from two datatables and filter it to another datatable. Please see the example below:
First datatable:
Second datatable:
If category matches class I filter it to the third datatable:

Currently, my solution is to go throw two loops and compare if it matches by these columns, but if I have huge amount of data it is working too slow. Maybe someone has different ideas on how to achieve it in a more optimized way?

For this scenario the Join task is used and can be done Join DataTable Activity or with LINQ

For an initial starter help on both find demo xaml here:
DT_Join_1Col.xaml (10.0 KB)