It always helps us to help you if you provide at least a basic list of hardware specs of your PC/Laptop.
Laptop/Desktop? What CPU (Intel or AMD and what model/speed)? What Video Card (Nvidia, AMD or integrated Intel)? How much RAM installed (8GB, 16GB, 32GB)? Which OS you running (Windows, Linux, MAC)?? Is it a brand named computer? If so, Make and Model number? Custom built PC?
If you are not able to easily identify your specs, install and run CPU-Z (free and safe), it will scan and detect what hardware you are running and you can relay that information back over to us: https://www.cpuid.com/softwares/cpu-z.html
Otherwise, we can't really help you unless you provide more information so we can narrow down the issue.
Remember, the new Unity version uses a different game engine which requires a bit more power from your PC than the Java version (Video Card in particular).