Google App Script Timeout due to slowness - google-apps-script

Question

This would be my first time posting, so I am sorry for the things I may or may not write.
I have a working Google Script which gets a file from an URL, parses the JSON then feed the data to a google Spreadsheet, one row at a time.
The problem that I have is that some of these files are large, 7000 rows large, which the script is unable to feed in the given time of 6 minutes. The speed of which it processes each row is quite slow, it is about 1 row every 1-3 seconds.
I believe that the problem is with the for clause, but I cannot seem to make it work.
I am not that experienced with this kind of scripting, and this was made from "inspirations"
Is there a way to speed up the for process in order to fill out the sheet faster, so it wont timeout?
SpreadsheetApp.getUi()
.createMenu('Update')
.addItem('Refresh Report', 'getData')
.addToUi();
}
function getData() {
var ss = SpreadsheetApp.getActiveSpreadsheet();
//var sheets = ss.getSheets();
var datasheet = ss.getSheetByName('Data');
var hasCreatedHeaders = false;
//Url
var url = 'URL HERE';
//Create header
var headers = {
'Content-Type': 'application/json',
'Authorization': 'xxx'
};
//Options
var options = {
'method': 'get',
'headers': headers
};
var response = UrlFetchApp.fetch(url, options);
var json = response.getContentText();
var data = JSON.parse(json);
var table = data.Table1;
datasheet.clear();
//foreach row
table.forEach(function(row) {
var cols = [];
var headers = [];
for (var prop in row.Columns) {
if (!hasCreatedHeaders)
headers.push(prop);
cols.push(row.Columns[prop]);
}
if (!hasCreatedHeaders) {
datasheet.appendRow(headers);
hasCreatedHeaders = true;
}
datasheet.appendRow(cols);
});
}

Answer 1

Try to change the loop table.forEach() this way:
//foreach row
var table_new = []; // <--- create a new empty array
table.forEach(function (row) {
var cols = [];
var headers = [];
for (var prop in row.Columns) {
if (!hasCreatedHeaders)
headers.push(prop);
cols.push(row.Columns[prop]);
}
if (!hasCreatedHeaders) {
// datasheet.appendRow(headers);
table_new.push(headers); // <--- add row to the array
hasCreatedHeaders = true;
}
// datasheet.appendRow(cols);
table_new.push(cols); // <--- add row to the array
});
// put the array on the sheet all at once
datasheet.getRange(1,1,table_new.length,table_new[0].length).setValues(table_new);
The problem is appendRow() method is quite time consuming. If you create the table as a 2D array you can put it on the sheet in one step with setValues() method. It's much faster.
References
Best practices