How to use editor:true feature in uitable?

Where did you placed this? In a function node? This won't work as a function node runs on the backend but tabulator in the front end. This is why the call back function has to be send inside a msg.ui_control structure as a string to the frontend and will be "handed over" to tabulator by ui-table (using the new Function ('','') constructor)

{
    "tabulator": {
        "cellEdited": "function(cell){     debugger;     this.send({         ui_control:{callback:'cellEdited'},                  payload:cell.getValue(),         oldValue:cell.getOldValue(),         field:cell.getColumn().getField(),         id:cell.getRow().getIndex()     });  }"
    }
}

See the little difference? your code snippet defines the function in the backend where the example nodes send the code as a string:

image

done correctly it should trigger the debugger (browser):

image

here are the modified nodes form example #6

[{"id":"7b6490b3.cd9c7","type":"function","z":"c4712650.59b5e8","name":"callback function(s)","func":"// how to use the editor to write callback functions\n// DO NOT wire this into your flow!\n// copy / paste \"function( ... }\" into the correct calback parameter\n// use the visual JSON Editor in order to take care formating inverted commas\n// use the \"debugger\" statement to debug your callback inside your browser\n\nvar topCalc = function(values, data, calcParams){\n    var total = 0;\n    var calc = 0;\n    var count = 0;\n    data.forEach(value => {\n        total+=Number(value.numberValue);\n        count++;\n    });\n    if (count>0) calc=(total/count).toFixed(2);\n    return `${calc} (avg)`;\n}\n\nvar legend = function (value) {\n    if (value<100) return \"<span style='color:#FF0000;'>\"+value+\"</span>\";\n    else return \"<span style='color:#000000;'>\"+value+\"</span>\"; \n}\n\nvar cellEdited = function(cell){\n    debugger;\n    this.send({\n        ui_control:{callback:'cellEdited'},         \n        payload:cell.getValue(),\n        oldValue:cell.getOldValue(),\n        field:cell.getColumn().getField(),\n        id:cell.getRow().getIndex()\n    }); \n}\n\n// used by the button column\nvar btnFormatter = function(cell, formatterParams, onRendered){\n    return '<button class=\"md-raised md-button md-ink-ripple\">Activate</button>';\n}","outputs":1,"noerr":0,"initialize":"","finalize":"","x":923,"y":782,"wires":[[]]},{"id":"ce8d3904.be1b08","type":"ui_button","z":"c4712650.59b5e8","name":"","group":"ff9fdb9a.7da098","order":21,"width":"4","height":"1","passthru":false,"label":"inject cellEdited callback","tooltip":"","color":"","bgcolor":"","icon":"","payload":"function(cell){     debugger;     this.send({         ui_control:{callback:'cellEdited'},                  payload:cell.getValue(),         oldValue:cell.getOldValue(),         field:cell.getColumn().getField(),         id:cell.getRow().getIndex()     });  }","payloadType":"str","topic":"cellEdited","topicType":"str","x":280,"y":1071,"wires":[["16664cef.5b26b3"]]},{"id":"ff9fdb9a.7da098","type":"ui_group","name":"TEST","tab":"7dcc246f.ee661c","order":1,"disp":false,"width":"8","collapse":false},{"id":"7dcc246f.ee661c","type":"ui_tab","name":"TEST","icon":"dashboard","order":3,"disabled":false,"hidden":false}]

Perhaps take a look on the browser debug console for any errors.

Perhaps you can send me your node(s) how you plan to do this.

The tooltip peformance problem is totally tabulator internal - I used tabulator with more than 500k lines until chrome quits with out of memory error (but without tooltips) .... perhaps the upcoming upgrade can help here (Failure to create my first UI table - #23 by Christian-Me but not easy to install from my fork)