I recommend you have the new records created as linked records in a different table. That way you will not have so much duplicate information.
Can you clarify your goals?
Is this an automation script? Automation scripts are limited to 30 seconds.
Can you change this to a scripting app that is run from a button to avoid the time limitation?
I suspect that your script is already creating records in batches of 50. (200 original records times an average of 6 new records would take about 30 seconds to create). However, it is possible to create all the records you need using a different technique that I call mega batches. With mega batches, you could create all the records you need (600 x 12) in well under 30 seconds.
If you are interested in hiring me to implement a script with mega batches, you can book an appointment with me to discuss options.