Leander,
Thanks for the call. as you mentioned the problem lays in the loading time of reading the DomInstances because your architecture has a DomDefinition where 1 of it's section has multiple records you don't need at that point of your flow. And you would like to read out the instance without the impact of this section.

I do not think it is possible today to exclude a section from the Read since you are asking to read the full Instance (and not just a specific section or sections)

There are a few things I can advise to improve the speed:

1. Change the architecture of your DOM Module. I personally always make a new Dom Definition as soon as there is a 1-to-many relation. I like to view things as basic Database architecture and see a Dom Definition as a Table. So, when I have multiple rows that should link to 1 other row I will create 2 tables. => 2 Dom Definitions.
   I believe this will make the most impact and provide you with more control what and how to do things.
2. Use a helper to process big data chunks:
   Example: (Tools is part of Skyline.DataMiner.Net)
   public static List<DomInstance> GetDomInstances(this DomHelper domHelper, List<Guid> instanceIds)
   {
   var instances = Tools.RetrieveBigOrFilter(
   instanceIds,
   id => DomInstanceExposers.Id.Equal(id),
   filter => domHelper.DomInstances.Read(filter));

   return instances;
   }

3. Use paging. This is useful when processing is needed based on the result. I think it is not applicable to your use case as you want to always show all the DomInstances (based on your filter) in the low code app table.
   Example: (this will get all instances based on a field descriptor, kind of the select * where field = "hello" )

   public static List<DomInstance> GetAllDomInstanceByFieldValueByPages(this DomHelper domHelper, FieldDescriptor fieldDescriptor, string value)
   {
   var filter = DomInstanceExposers.FieldValues.Field(fieldDescriptor.ID.Id.ToString()).Equal(value);
   var allDomInstances = new List<DomInstance>();
   var pagingHelper = domHelper.DomInstances.PreparePaging(filter);
   while (pagingHelper.MoveToNextPage())
   {
   var currentPage = pagingHelper.GetCurrentPage();
   allDomInstances.AddRange(currentPage);
   }

   return allDomInstances;
   }
   Don't just copy this last example as it has no value it this form. It's simply an example how to use it. Instead of adding it to a list, one should add logic to process the currentPage before moving to the next.