Cocoa App hangs when using NSTextView with NSScrollView - objective-c

Question

I am reading some file content and trying to display on NSTextView with NSScrollView.
My app hangs when I try to display the content of a very large file. The actual scenario is:
open the file.
Read its content in NSData and convert it to NSString.
Create a NSScrollView.
Create a NSTextView.
Set the above created NSString to NSTextView.
File Size is extremely large . It contains around 106010441 lines.
My app is successfully able to show the inital content of the file, until I scroll down it starts hanging and become very slow.
If I click on text area and press command + a to select all and start scrolling, it completely freezes.
I dont know , what I am doing wrong.
Here is my ViewController.m content:
#import "ViewController.h"
#implementation ViewController
- (void)viewDidLoad {
[super viewDidLoad];
/
NSString * path = Path_to_file;
NSFileHandle * fileHandle = [NSFileHandle fileHandleForReadingAtPath:path];
NSData * buffer = [fileHandle readDataToEndOfFile];
raw_string = [[NSString alloc] initWithBytes:[buffer bytes] length:[buffer length] encoding:NSUTF8StringEncoding];
}
- (void)setRepresentedObject:(id)representedObject {
[super setRepresentedObject:representedObject];
}
- (IBAction)button:(id)sender {
_Scroller.hasVerticalScroller = YES;
_Scroller.hasHorizontalScroller = YES;
_Scroller.autoresizingMask = NSViewWidthSizable | NSViewHeightSizable;
NSSize contentSize = _Scroller.contentSize;
NSTextView* _textView = [[NSTextView alloc] initWithFrame:NSMakeRect(0, 0,
contentSize.width, contentSize.height)];
_textView.minSize = NSMakeSize(0.0, contentSize.height);
_textView.maxSize = NSMakeSize(FLT_MAX, FLT_MAX);
_textView.verticallyResizable = YES;
_textView.horizontallyResizable = YES;
_textView.autoresizingMask = NSViewWidthSizable;
_textView.textContainer.containerSize = NSMakeSize(contentSize.width, FLT_MAX);
_textView.textContainer.widthTracksTextView = YES;
_textView.automaticSpellingCorrectionEnabled = NO;
_textView.continuousSpellCheckingEnabled = NO;
_Scroller.documentView = _textView;
_textView.string = raw_string;
}
#end