What is the fastest way to update a google spreadsheet with a lot of data through the spreadsheet api?

I was able to speed up the batch request provided in the official API http://code.google.com/apis/spreadsheets/data/3.0/developers_guide.html#SendingBatchRequests by skipping the QUERY part before the UPDATE. So this is what they have in the example:

// Prepare the update
    // getCellEntryMap is what makes the update fast.
    Map cellEntries = getCellEntryMap(ssSvc, cellFeedUrl, cellAddrs);

    CellFeed batchRequest = new CellFeed();
    for (CellAddress cellAddr : cellAddrs) {
      URL entryUrl = new URL(cellFeedUrl.toString() + "https://stackoverflow.com/" + cellAddr.idString);
      CellEntry batchEntry = new CellEntry(cellEntries.get(cellAddr.idString));
      batchEntry.changeInputValueLocal(cellAddr.idString);
      BatchUtils.setBatchId(batchEntry, cellAddr.idString);
      BatchUtils.setBatchOperationType(batchEntry, BatchOperationType.UPDATE);
      batchRequest.getEntries().add(batchEntry);
    }
  // Submit the update
    Link batchLink = cellFeed.getLink(Link.Rel.FEED_BATCH, Link.Type.ATOM);
    CellFeed batchResponse = ssSvc.batch(new URL(batchLink.getHref()), batchRequest);

and this is what I changed it to

CellFeed batchRequest = new CellFeed();
        for (CellInfo cellAddr : cellsInfo) {
             CellEntry batchEntry = new CellEntry(cellAddr.row, cellAddr.col, cellAddr.idString);
              batchEntry.setId(String.format("%s/%s", worksheet.getCellFeedUrl().toString(), cellAddr.idString));         
              BatchUtils.setBatchId(batchEntry, cellAddr.idString);
              BatchUtils.setBatchOperationType(batchEntry, BatchOperationType.UPDATE);  
              batchRequest.getEntries().add(batchEntry);



        }

        CellFeed cellFeed = ssSvc.getFeed(worksheet.getCellFeedUrl(), CellFeed.class);      
        Link batchLink =  cellFeed.getLink(Link.Rel.FEED_BATCH, Link.Type.ATOM);

        ssSvc.setHeader("If-Match", "*");
        CellFeed batchResponse = ssSvc.batch(new URL(batchLink.getHref()), batchRequest);
        ssSvc.setHeader("If-Match", null);

Notice, the header should be changed to make it work.