Hi,
If you were setting it to unlimited and that was really taken into account by your server, then you wouldn't have that error message since it can only happen when the processing reaches the limit and by definition, unlimited doesn't have a limit.
So I suppose that you still have a limit.
Instead of 0, try a big value.
Also, HikaShop can import products data really rapidely and even with 10K products, it should only take a few seconds. So that means that you have something else in the CSV which takes time.
For example, if you have image URLs in your CSV, then each time the CSV is processed, HikaShop has to download each image, and for each one, it can take several seconds or even 10s of seconds if the image is big. So if you have image URLs, try to upload them separately in the images/com_hikashop/upload folder of HikaShop and instead have their relative path in your CSV.