Limits of number of taxonomie

I want to migrate/convert an existing e-commerce site into wordpress platform with a ecommerce plugin (probably woocommerce).
Actually the site have a lot of number of product (about 170.000) with many attribute (writer, publisher, genre, series) and all items are updated every week many times from a external file.
These are the numbers of items updates (more or less):
– product (titles od books): 170000
– genre (custom category): 350
– writers (custom attribute -> taxonomy): 130000
– publisher (custom attribute -> taxonomy): 3000
– series (custom attribute -> taxonomy): 20000
Now the problem: when i import data the process works but writers are not totally loaded and import stop at 52490 items and wp_term_taxonomy has 52875 record.
Why? Is a limit of wordpress or a php?
Perhaps wp load all taxonomie in memory and is is a system limit?
Thanks