Our form is almost similar to the standard NetSuite form, perhaps only five custom fields added. Our customer process is not that complicated so the NS basic design already supports what we needed.
I guess you'd have to work on performing a health check on your customer forms. Allow me to ask these questions:
Why did it get extremely customized in the first place?
Are all the fields necessary to perform daily tasks involving customers?
Are there any fields that you can inactivate?
How about restricting the fields/tabs to some roles or customizing forms per role so that users will just see the fields they need to see?