Merge addon highlights all lines as changed for large file with loads of changes

Am using the merge addon to show diff between 2 file content, when I have large number of changes between the files , all the lines are highlighted as changed.
I assume its something to do with the google match patch library timing out maybe.
Is there any advice on this.
Size of file is around 80k lines , number of deltas could be around say 5k.

Let me know if more details needed.
Initialization code:
mergeView = CodeMirror.MergeView(target, {
value: “Loading Data”,
orig: “Loading Data”,
origLeft: null,
lineNumbers: true,
mode: “text”,
showDifferences: true,
collapseIdentical: false,
readOnly: true,
revertButtons: false,
coverGutterNextToScrollbar: true,
lineWrapping: true,
I am fetching the file content via AJAX and on getting the file content , i do the following:

to set the left and right editor content.

Thanks in advance.