1/ The idea is to read a CSV file, and create an item with its properties
for each line. So I have to loop over thousands of lines and create an item
and multiple claims associated, and it takes quite some time to do so.
(atleast 1 hour to create 1000 items) I guess it's because for each line, I
create a new entity and new claims, which means multiple requests for each
line.
There is an API call, wbeditentity [1] that allows preparing an item with
multiple claims which are written to WB in one call. its Are you aware of
wikibase universal bot [2] and wikibase-tools [3]? Both cover functionality
that should allow to do what you describe above and both use the
wbeditentity call.
[1]
https://www.wikidata.org/w/api.php?action=help&modules=wbeditentity
[2]
https://github.com/dcodings/Wikibase_Universal_Bot
[3]
https://github.com/stuppie/wikibase-tools