Solution 1:

why don´t you try to use google API for direction, based on basic http requests. https://developers.google.com/maps/documentation/directions/ . (check the conditions on licensing and nº of requests).

And then plot the the data with IOS MKPolyline. i´m Sure you will have better performance. And you will only depend on google for the positioning data.

to convert the response from google API to coordinates, use the well known method (taken from other post) below:

- (NSMutableArray *)parseResponse:(NSDictionary *)response
{
    NSArray *routes = [response objectForKey:@"routes"];
    NSDictionary *route = [routes lastObject];
    if (route) {
        NSString *overviewPolyline = [[route objectForKey: @"overview_polyline"] objectForKey:@"points"];
        return  [self decodePolyLine:overviewPolyline];
    }
    return nil;
}


-(NSMutableArray *)decodePolyLine:(NSString *)encodedStr {

    NSMutableString *encoded = [[NSMutableString alloc]initWithCapacity:[encodedStr length]];
    [encoded appendString:encodedStr];
    [encoded replaceOccurrencesOfString:@"\\\\" withString:@"\\"
                                options:NSLiteralSearch range:NSMakeRange(0,
                                                                          [encoded length])];
    NSInteger len = [encoded length];
    NSInteger index = 0;
    NSMutableArray *array = [[NSMutableArray alloc] init]; NSInteger lat=0;
    NSInteger lng=0;
    while (index < len) {
        NSInteger b; NSInteger shift = 0; NSInteger result = 0; do {
            b = [encoded characterAtIndex:index++] - 63; result |= (b & 0x1f) << shift;
            shift += 5;
        } while (b >= 0x20);
        NSInteger dlat = ((result & 1) ? ~(result >> 1)
                          : (result >> 1)); lat += dlat;
        shift = 0; result = 0; do {
            b = [encoded characterAtIndex:index++] - 63; result |= (b & 0x1f) << shift;
            shift += 5;
        } while (b >= 0x20);
        NSInteger dlng = ((result & 1) ? ~(result >> 1)
                          : (result >> 1)); lng += dlng;
        NSNumber *latitude = [[NSNumber alloc] initWithFloat:lat * 1e-5]; NSNumber *longitude = [[NSNumber alloc] initWithFloat:lng * 1e-5];
        CLLocation *location = [[CLLocation alloc] initWithLatitude: [latitude floatValue] longitude:[longitude floatValue]];
        [array addObject:location]; }
    return array;
}

I had a similar problem with performance on google sdk and it work for me.