invoke function take long time

[Xiaobaishushu25]

I'm currently facing an issue where I'm trying to receive an image from the frontend and write it to the hard disk on the backend. I've already implemented asynchronous programming in Rust, but the invoke function still takes a long time (several seconds, increasing as the image size grows).this is my front code：

    startTime = new Date().getTime();
      await invoke("append_chunk_to_file", {path: path, chunk: chunk1,end:i==numChunks-1})
      endTime = new Date().getTime();
      console.log(`invoke took ${endTime - startTime} milliseconds.`);//invoke took 4469 milliseconds.

this is my rust code,i have use anysc:

#[tauri::command]
async fn append_chunk_to_file(window:Window,path: String, chunk: Vec<u8>,end:bool) -> Result<(), String> {
    println!("start{:?}",Instant::now());//start Instant { t: 644913.1384745s }
    tokio::spawn(async move{
        let mut file = OpenOptions::new()
            .create(true)
            .append(true)
            .open(&path)
            .map_err(|e| e.to_string()).unwrap();
        file.write_all(&chunk).map_err(|e| e.to_string()).unwrap();
        if end {
            window.emit("insert",Payload{message:path}).unwrap();
        }
    });
    let instant = Instant::now();
    println!("end{:?}",instant);//endInstant { t: 644913.1386845s }
    Ok(())
}

this is run capture:

It can be seen that the rust function does not take much time, but the invoke takes a long time, where did it take？