It's difficult to say without doing some real analysis.
It could be that the code to do the import is just not well written. It could be your Disks are old and slow. Probably nothing you're going to be able to quickly do except maybe check and see if RAM is an issue. The other items you probably just can't really fix without a lot of time / cost or both.
If your database is 150+MB then you have to be low on memory usage with 256MB for the entire system. If the database is less than that then memory might be okay.