I'm only importing ID, Stock QTY and Price with "Skip thumbnails regeneration" Enabled. I'm not uploading new product, just updating prices and stock.
Updating 10+ products is not an option as I need to update 25000 products daily.
The csv file i'm using uploaded without any errors on my other website so this must be a server or website problem. I have also tried different hosting and PHP settings as per above post.