Changing image size in Construct 2 vs editing size in editor

In a project sometimes you start off using a common image size and a general plan. Whether you realize it or not, during the process of working on your project it will start communicating to you. It starts telling you to change certain things or to take things in a different direction, it is only limited to your ability to accomplish what is being asked. That being said...

I have plenty of objects that are 64x64 and after working for a while I realized it will look better if many objects were half the size. My question is does making an objects size smaller in Construct 2 using it's Common Properties take up more resources during game play than using a 3rd party image editor and saving 40+ images to half the size and putting them back into Construct 2? It normally wouldn't matter if it were a small game, but the game that is being made has a lot of potential to grow in a lot of different directions and I have to optimize everywhere. If it doesn't take up resources other than the extra kb from image size than I would like to save the time. Thanks in advance.

As far as I know the engine will load the source image file into the memory regardless the size you set in the editor. So if you plan on saving resources your better option would be to resize all of your images in an image editor. However (since I'm not entirely sure about this) you might want to wait for an other developer to confirm this.

I was thinking it did that too, but wasn't to sure.

Unconnected

Going from 64x64 to 32x32 is not going to make much of a difference unless you have 1000's of objects. And you might want to keep the extra detail if you want to do a version for higher res screens.

You can re-size images inside the C2 image editor. Click on the resize icon at the top (between crop and zoom in). Resizing can be applied to all animation frames at the same time. You may have to reset image points/ origin as well...

(changing the size by adjusting its properties will not make any difference - as you suspected, but resizing it in the image editor will).

The image you see in the image editor is the source image. Objects in the layout are always rendered from the source image and stretched to their display size. So resizing objects in the layout has no effect on the source image. The source image will be fully loaded in memory regardless of the display size, but resizing an image from 64x64 to 32x32 will only save about 12kb of memory, so it's kind of pointless to do it in the name of memory. In this case I think just stretching them in the layout view is fine.

What is the unit of measurement for the size of an image in Construct 2 (pixels, inches, points)?

I am not sure what you mean. If you make a 32x32 pixel image then it will be 32x32 in C2.