As you probably know, data source queries take its time and OData queries are extremely slow.
To speed up output generation, I want to limit data source access as much as possible:
Often I have to iterate multiple times through the same amount of data by use of a forEach tag.
At present it is the case that I have to query the data source for each forEach loop.

From my point of view it would be an advantage if the queried data of a forEach loop is (optionally) stored in a dataset accessible at different positions in the template during output generation.
(This could be indicated by an additional property of the forEach tag.)

Example:

${varNameOne} = [forEach:] (OdataDatasource:ODataEntity?$filter=x eq y) [:forEach] /ForEachProperty:keepData=true

-> This is a (slow) data source access
-> The records are stored in a dataset with name "varNameOne"

-> Later in the template: again access to that records:

${varNameTwo} = [forEach:] (${varNameOne}?$filter=a ne b) [:forEach]

-> This is a (fast) memory access

That applies not only to a forEach tag, but also to a Query tag, what would just result in a single record dataset.