Yes, that's normal.
You have too much possibilities. For example, if you have 3 characteristics with 10 values each, that's 10*10*10=1000 possibilities. That's already too much.
You should indeed transform some characteristics into custom fields (
www.hikashop.com/en/support/documentatio...p-field-listing.html
) or options (
www.hikashop.com/en/support/documentatio...ct-form.html#options
) so that it becomes more manageable for your server.
Characteristics should only be used when you want to change some of the information on the products (the stock, the price, the image, etc). For choices which do not affect any of that custom fields of the table "item" are the way to go.