Fast Converting RenderTexture to Texture2D

I have a screenshot preview at the end of the game's level. When I am loading the screenshot, it makes game freeze for a moment. What shall I do, so there would be no freeze, when I am loading that screenshot? Here is mycode:

 private IEnumerator ShowScreeshotPreview()
         {
     screenshotTexture = new Texture2D(Screen.height, Screen.height, TextureFormat.RGB24, false);
             for (int i = 0; i < 9; i++)
             {
                 yield return null;
             }
             RenderTexture.active = Singletons.Get<SpecialEffectsHelper>().MainCharacterScript.GetComponent<GeneratorScript>().screenshotTexture;
             screenshotTexture.ReadPixels(new Rect(0, 0, Screen.height, Screen.height), 0, 0);
     screenshotTexture.Apply();
             RenderTexture.active = null; //Added to avoid errors
     
             screenshotPrview.mainTexture = screenshotTexture;
     ScreenshotPreviewAnimator.SetBool("visible", true);
             screenshotLoaded = true;
     
             yield return null;
         }