Is jos_redirect_links used by Hikashop?

We have close to 30 000 products in our Hikashop and our hosting company is complaining that the site takes to much CPU and that it is crashing the server.

We only have about 500 visitors a day but they click on 20 pages each on average but I feel the server should be able to handle it.

What could I change to make the load less on the server?

I feel that there is something wrong with my DB and one thing that sticks out is the jos_redirect_links and it is 150 mb.

The second biggest in DB is arround 12 mb (hikashop categories table) and all the others small at size.

Is this correct that the jos_redirect_links is so large compared to everything else?

That table is not used by HikaShop but by Joomla redirect system.

One easy way to reduce the load is to use cache. But there can be some problems with cache as some pages need to be dynamic like the checkout, so you might want to use something more advanced than the default cache system of Joomla where you can control where can the cache apply:
extensions.joomla.org/extensions/site-management/cache/13155

Also, you should try to clean that redirect_links table. It's not normal that it is so big.

Thanks Nicolas will try the chache

Should I optimize or empty the table?

You could try but before, make a copy/export in case something goes wrong so that you can easily restore it if needed.

I have created a backup now, should I empty it?

Yes, you should try.