Efficiency of temporary variables (e.g java)

I was wondering if there is a difference in efficiency or performance when working with temporary variables inside constructors or methods.

Here is an example

    // Get bufferedImage
    BufferedImage trayIconImage = ImageIO.read(getClass().getResource("/images/D.gif"));

    // Calculate width
    int trayIconWidth = new TrayIcon(trayIconImage).getSize().width;
    
    // Create TrayIcon
    TrayIcon trayIcon = new TrayIcon(trayIconImage.getScaledInstance(trayIconWidth, -1, Image.SCALE_SMOOTH));

So I have a temporary variable "trayIconWidth"

But I also could do this like so:

    //Get bufferedImage
    BufferedImage trayIconImage = ImageIO.read(getClass().getResource("/images/D.gif"));

    // Create TrayIcon
    TrayIcon trayIcon = new TrayIcon(trayIconImage.getScaledInstance(new TrayIcon(trayIconImage).getSize().width, -1, Image.SCALE_SMOOTH));

So basically I am skipping the step of getting the int value for the width.

There are a lot of examples where you can skip multiple temporary variables and I know that it has to do with readability and stuff. But I would like to know if there is any difference in speed, performance, efficiency, or ram usage.

Does the (e.g. java) garbage collector handle this kind of temporary action?

EDIT 1:

I compared the bytecode of two basic snippets. They are different. second

So this means the pc has to do one or more instructions to get the execution done - am I right?

regards Nur1