Improve performance of updating 'progress' column

src/webui/www/public/scripts/dynamicTable.js

@@ -32,6 +32,7 @@
  **************************************************************/
 
 var DynamicTableHeaderContextMenuClass = null;
+var ProgressColumnWidth = -1;
 
 var DynamicTable = new Class({
 
@@ -851,25 +852,34 @@ var TorrentsTable = new Class({
 
                 if (td.getChildren('div').length) {
                     var div = td.getChildren('div')[0];
-                    var newWidth = td.offsetWidth - 5;
-                    if (div.lastWidth !== newWidth) {
-                        div.setWidth(newWidth);
-                        div.lastWidth = newWidth;
+                    if (td.resized) {
+                        td.resized = false;
+                        div.setWidth(ProgressColumnWidth - 5);
                     }
                     if (div.getValue() != progressFormated)
                         div.setValue(progressFormated);
                 }
-                else
+                else {
+                    if (ProgressColumnWidth < 0)
+                        ProgressColumnWidth = td.offsetWidth;
                     td.adopt(new ProgressBar(progressFormated.toFloat(), {
-                        'width' : td.offsetWidth - 5
+                        'width' : ProgressColumnWidth - 5
                     }));
+                    td.resized = false;
+                }
             };
 
             this.columns['progress'].onResize = function (columnName) {
                 var pos = this.getColumnPos(columnName);
                 var trs = this.tableBody.getElements('tr');
-                for (var i = 0; i < trs.length; i++)
-                    this.columns[columnName].updateTd(trs[i].getElements('td')[pos], this.rows.get(trs[i].rowId));
+                ProgressColumnWidth = -1;
+                for (var i = 0; i < trs.length; i++) {
+                    var td = trs[i].getElements('td')[pos];
+                    if (ProgressColumnWidth < 0)
+                        ProgressColumnWidth = td.offsetWidth;
+                    td.resized = true;
+                    this.columns[columnName].updateTd(td, this.rows.get(trs[i].rowId));
+                }
             }.bind(this);
 
             // num_seeds