A few hours is a pretty long time for a CPU to be running at near-T-Junction temps. On top of that, every time I pull from a larger repo or unzip a large folder, MacOS will decide it's time for me to take a quick 2 hour break while it depletes 60% of it's battery. Instead of setting up a complicated ignorelist, I just disabled Spotlight indexing altogether.
If the content of the folder or repo have thousand of files and folders, then it would made sense for Spotlight to index them all.
It the same for transferring the folder/files to other location. a single 1GB file will take 5 second to transfer to external hard drive. A 1GB non-zipped folder (consists of thousands of thousand file from 1KB to 1MB each) will take half hour or more to transfer to external drive. I have a 150GB folder that contains over 500k of files, averaging 120KB to 4 MB, will take 3 hours to transfer to the external drive. I have another 120GB folder that are consist of videos, averaging 300MB to 10GB, took 20 minutes to completely transfer to external drive. This transfer through NVMe ---> spinning rust external drive through USB 3.1.
If you are pulling a large repo that have thousands of files in it will take a while for Spotlight to index each file. That is not the fault of Spotlight, that is just the way it is because it have to scan individually each file to index.
I do wish it was faster. I will say, however, that I never really noticed it on my new M1 macbook. They made it less intrusive, I guess. It used to be quite bad for a few hours and I'd sometimes just walk away and grab lunch, or time my new system install for bedtime. Perhaps the switch to SSDs helps as well, it's easy to forget how slow laptop spinning rust was.
