My iPhoto freezes when I try to drag a picture from one album to another

Ok - next thing I'd try:

Try restarting your mac in safe mode and then trying.

Then restart normally, and try again.

Safe mode will clear temporary files and caches, and sometimes fixes odd glitches such as this.

Start up your Mac in safe mode – Apple Support (UK)

Do you mean iPhotos? Or the Photos app that replaced iPhotos some years ago?

Where is your library stored? On your system drive, or somewhere else? If on an external drive, what is the format?

Do you run any security software, or clean up/duplicate removal apps?

iPhoto doesn't come with macs anymore. It is Photos

If you have MacOS 10:15 as shown in your OP then you should have the Photos app. Now might be the time to start using it. It can upgrade your iPhoto library for you so you don't lose anything. (Or not much anyway - there are some iPhoto facilities not matched in photos, such as events. These are converted to albums - there may be other limitations)

Mark Tony's post as solved so he gets the credit and others will know there's a fix in this topic.