Macos 键入期间NSTextView延迟

我有两个带有共享自定义NSTextStorage子类的NSTEXTVIEW。文本视图相互镜像内容。在我按enter键之前，这一切正常。然后第二个文本视图开始滞后，甚至不显示任何新输入。无论我输入哪个文本视图，都会发生这种情况

如何强制第二个textview与第一个textview保持同步

这是我的NSTextStorage子类

@implementation MyTextStorage
{
    NSTextStorage *_backingStore;
}


-(id) init
{
    self = [super init];
    if (self)
    {
        _backingStore = [[NSTextStorage alloc] initWithString:@""];
    }
    return self;
}

-(NSString *) string
{
    return [_backingStore string];
}

-(NSDictionary *) attributesAtIndex:(NSUInteger) location
                     effectiveRange:(NSRangePointer) range
{
    NSMutableDictionary *attributes = [[_backingStore attributesAtIndex:location
                                                         effectiveRange:range] mutableCopy];

    if ([self displayMode] == MyTextStorageDisplayNormal)
    {
        [attributes setObject:[NSColor blackColor]
                       forKey:NSForegroundColorAttributeName];//remove syntax coloring
    }
    return attributes;
}


#pragma mark - editing
-(void) replaceCharactersInRange:(NSRange)range
                      withString:(NSString *)string
{
    [_backingStore replaceCharactersInRange:range
                                 withString:string];
    [self edited:NSTextStorageEditedCharacters
           range:range
  changeInLength:[string length] - range.length];
}


-(void) setAttributes:(NSDictionary *) attributes
                range:(NSRange) range
{
    [_backingStore setAttributes:attributes
                           range:range];

    [self edited:NSTextStorageEditedAttributes
           range:range
  changeInLength:0];
}