Find a combination of three variables

[Kaisa77]

Hi, I'm working on a workflow and my solution works, but it takes too long. I was hoping somebody would suggest a better approach. 

I have three lists of variable. The information in these lists could be duplicated. Each variable has a key assigned to it (also not unique). I also have a master dataset where I need to find all combinations of these variables only when their ID's match. 
I'm using append to create all combinations, but for just a third of actual data it takes me 15 minutes to run. 

For simplicity, in my example below I will only use two sets of variables
List one: ID    Variable1

                1     A

                1     B

                 2    B

List two: ID    Variable2

                1     c

                1    d        

                2    e

In my dataset, where I have variables 1 and 2 as fields, I need to find the following combinations (I'll write ID's in the parentheses): 

Variable 1   Variable 2

(1) A                 (1) c

(1) A                 (1) d

(1) B                 (1) c

(1) B                 (1) d 

(2) B                 (2) e

I don't need a combination of A/e because their ID's never match. 

Like I said, I use append to get the combinations and then the filter tool to remove ones where ID's don't match, but got more than million combinations. 
What other tool/logic could help me?

[JessieC]

@Kaisa77 ,

I tried a Transpose + Join, but it wasn't faster than Append + Filter. See attached.

[PhilipMannering · Accepted solution]

I think what you want to do is join on ID,

wf

[Kaisa77]

OF COURSE!

Thank you so much, Join by ID works just like Append did, but runs 5 times faster and no need to filter out unneeded combinations.