I have not yet done so, but I would expect that it is feasible to insert 1000 rows in a single mysql statement.
To do so, I would direct the json output of the node-red-contrib-spreadsheet-in to a change node that has a jsonata query that is creating your multiple record sql insert statement
Take care that node-red-contrib-spreadsheet-in might produce a "sparse array" in case the excel has blank cells and a "sparse array" is not proper json (so this might give unexpected results when using jsonata query). You can convert it to proper json by directing the output to 2 json nodes in series. For more details see also this topic: Weird behaviour when processing an array of arrays having null values
