[Client] Random black boxes and severe lag?

Keep having random black boxes appear after game ends.

Client is also very laggy. Almost miss accept match button, nearly impossible to change runes before match begins. Pretty bad issue because I have been kicked from a lobby because I wasn't able to lock in champ in time due to lag.

Was not having this issue before the last couple of patches.

OS Name: Microsoft Windows 10 Home Adapter Description: AMD Radeon (TM) RX 560 Processor: AMD A10-9700 RADEON R7, 10 COMPUTE CORES 4C+6G, 3500 Mhz, 4 Core(s), 4 Logical Processor(s) Installed Physical Memory (RAM): 16.0 GB Total Virtual Memory: 35.4 GB Available Virtual Memory: 24.7 GB