Extremely slow small site workflow. Takes Hours and times out

Hi All, 

A site that I managed was recently migrated to 365 from on premise. 

I have a few site workflows but this one is taking forever to run, it has never completed. On premise, this workflow would take about 20 minutes. 

The workflow in a nutshell:

1. Build an email template
2. Query a list for ALL items (has about 2500 list items) to get user names (there are 12 users - This does not change often.
3. Remove duplicates.
4. for each user in the collection (where user = variable from step 2) 
   1. Query the list for the items for that use
5. For Each item found in the second query
   1.  set multiple variables (10 individual variables)
   2. Math: Add item to counter variable
   3. Build string adding the variables to an email template
   4. Build String: close the table
   5. Run if counter = 125
      1. pause for 2 minutes
      2. reset counter variable
   6. send email
   7. clear all collections

overall there are two queries and 2 for Each activities. I have no idea why this takes so long. It takes an hour just to get one email.

Any help here would be MOST appreciated.