I think the main problem is using GUI. Installing newer distro and running on GUI requires more RAM and processing power. You won't have that problem running only CLI. I installed older distro like Redhat 8.0 on my old computer, and running on lightweight window manager, WindowMaker. So, in conclusion, choose lightweight window manager if you want to run on GUI, and you may need to consider running on older distro, and yes, turn off all unnecessary services.
But some newer distro like Vector Linux is not bad for its speed