Client lags my computer

Whenever i update my client if I try to do anything else on my computer it starts to freeze and lag until the patch is finished. I have league on my SSD along with my windows so that's a possibility there, but i don't quite understand why it does that. Hopefully it's a simple fix, but i don't quite understand it.

Specs: Gigabyte AORUS Gaming K5 AMD Motherboard AMD Ryzen 7 1700x HyperX Savage 240gb SSD 16 GB G.Skill Trident Z 1tb Seagate 7200RPM HDD Windows 10