Performance issues - where to start looking for issues?

Hi.

My suggestions are:

- Try to always keep your project as organized as possible so you can better visualize which parts need more attention;

- Lower the number of instances and containers as much as possible;

- Use the most efficient and manageable instance type for each case. For example: you were using Movie Clips instances for the items in the scene and in the inventory and applying AS3 for hover effect. But it's much easier and efficient to use the default Button which will do this automatically for you. Also, you were duplicating the scene items for hit detection. This is not necessary. If you don't need a timeline, use Sprites instead of MovieClips, and so on.

- If you need mouse events for multiple instances that belongs to the same parent, assign one single listener to the parent and then check which instance received the event using the event.target property.

- Instead of creating various containers for animations of a same character, distribute the animations in one single container and assign labels to them;

- Avoid using very large bitmaps;

- Disable the advanced layers mode (Ctrl/Cmd + J) if you don't need it because this mode has some impact on performance;

- Your framerate was too high (120 fps). I think 60 fps is enough.

I grabbed your file and did a overal restructuring in your instances, timelines, and Library. I rewrote the code as well. I think it's easier to understand and maintain now.

You of course may need to apply some tweaks here and there but I think the general idea was kept.

AS3 code:

import flash.events.MouseEvent;
import flash.display.FrameLabel;
import flash.text.TextField;
function showDialog(e:MouseEvent):void
{
    for each (var s:FrameLabel in dialog.currentLabels)
    {
          if (s.name == e.target.name)
          {
              var textField:TextField;
              dialog.gotoAndStop(e.target.name);
              textField = dialog.getChildAt(0) as TextField;
              if (textField.numLines == 1)
                    char.gotoAndPlay("shortTalk");
              else
                    char.gotoAndPlay("longTalk");
              break;
          }
    }
}
function checkItem(e:MouseEvent):void
{
    if (e.target.name == "poster")
          inventory.cvinv.visible = true;
    else if (e.target.name == "laptop")
          inventory.triforce.visible = true;
    else if (e.target.name == "hat")
          inventory.pickles.visible = true;
    else if (e.target.name == "chair")
          inventory.rkcard.visible = true;
    else if (e.target.name == "paper")
          inventory.portfolioinv.visible = true;
    else if (e.target.name == "trash")
          credits.visible = true;
    else if (e.target.name == "karpfen")
    {
          sceneItems.karpfen.visible = false;
          sceneItems.log.visible = true;
          smoke.gotoAndPlay(1);
    }
    else if (e.target.name == "log")
    {
          sceneItems.karpfen.visible = true;
          sceneItems.log.visible = false;
          smoke.gotoAndPlay(1);
    }
}
function botherLuke(e:MouseEvent):void
{
    e.currentTarget.play();
}
function dismissCredits(e:MouseEvent):void
{
    if (e.target.name == "closeButton" || e.target.name == "hit")
          credits.visible = false;
}
function start():void
{
    sceneItems.log.visible = false;
    sceneItems.addEventListener(MouseEvent.MOUSE_OVER, showDialog);
    sceneItems.addEventListener(MouseEvent.CLICK, checkItem);
    inventory.addEventListener(MouseEvent.MOUSE_OVER, showDialog);
    luke.addEventListener(MouseEvent.CLICK, botherLuke);
    credits.addEventListener(MouseEvent.CLICK, dismissCredits);
}
start();

FLA download:
room_proto11_scaled_edited.zip - Google Drive

This is only a suggestion. You don't have to follow everything I did.

Regards,

JC