GetItems is the correct way to do. As a rule of thumb, batching is the fastest way possible

I'm not seeing how you load the variants

Generally speaking - if you think some code is slow, the next step is to profile it to find the bottleneck, then optimize. you are going right direction with GetItems so continue on that path ... 

Thanks!

Well, this GetItems call usually takes pretty long.

But will consider what you said.

For variants I then use 

product.GetVariants()

// or

var variantLink = _referenceConverter.GetContentLink(variantCode);
_contentLoader.TryGet(variantLink, out variant);

I did not find any way to optimize that call because I have some logic before getting the variants.

How many variants do you have for each product? If you have multiple, it could be faster to use IRelationRepository to get all variant links and get them in one go - again, with GetItems

How many items do you get in one go? I would suggest to start with 20 and optimize further. it sounds like you might get a big batch in one go and the db is the bottleneck. anyway, we can only rely on profiling results (I like dottrace) to make optimizations 

Thanks for the tip. I found some extra db calls that could be optimized after doing some profiling.