Additional thoughts on breaking up the query as mentioned already by Nic: your GL likely has numeric logic to it like 1 series are assets, 2 series accounts are liabilities, and so on. After your existing r3table.AddCriteria statement on line 26 you can add another AddCriteria to limit this query to only certain accounts like the following:
r3table.AddCriteria("AND RACCT LIKE '00001%'")
Then fill an additional r3table2 with additional accounts with a different account list:
r3table2.AddCriteria("AND RACCT LIKE '00002%'")
Then once you have all of your r3tables filled (however many you need), convert them to datatables and either merge them for further operations if needed or simply present them all to the parser:
api.Parser.ProcessDataTable(si, dt1, True, api.ProcessInfo)
api.Parser.ProcessDataTable(si, dt2, True, api.ProcessInfo)