For processors, I want good CPUs with fast, small caches? A large cache on each processor probably wouldn't help.

64 GB of RAM seems like way more than...

Can you create a temporary table (as a staging table) with the datatypes you want? You could insert the incoming data into desirable covariant data columns. From there...

I would try 10% as a guideline. But that may not be appropriate for your situation.

Have you considered using a trigger?