If you're unusually lagging and don't know why, follow the procedure below. Hope it helps.
Procedure:
Code:
1. Press [Ctrl] + [Shift] + [Esc] to start task manager.
2. Switch to the [Performance] tab at the top in task manager.
3. Click on the [Resource Monitor...] button at the bottom to open the resource monitor.
4. Switch to the [Network] tab at the top in resource monitor.
5. Right click on the process you want to terminate and choose [Exit Process] from the drop down menu.
NOTE: System, svhost.exe (Network Serive), LolClient.exe, LolPatcher are the only processes required to play League of Legends, so you might want to close everything but these processes.
Alternatively:
Anyone experiencing the same program showing up every time in their Resource Monitor should completely disable that program if they don't need it. (Google any program that shows up if you're not sure if you need it or not). You turn it off permanently by going to Start > Run > services.msc, find the program (you may have to Google the service name if it wasn't clear in Resource Monitor), and then set it to "Disable".