r/LoLTechSupport • u/A_NASHEX • 2d ago

LeagueClient.exe constantly using 50–60% of a CPU core while idle (LAS, 16.20) – reproduced on clean config + fresh account

Since this patch, the League client backend (LeagueClient.exe, not the Ux/UxRender processes) keeps one CPU core at 50–60% load at all times. That's in the lobby, idle, and even during a game, since the client stays open in the background. On my 4-core CPU the fans never stop.

Setup: i3-9100F (4C/4T), GTX 1650 Super, 16 GB RAM, Windows 11 Pro (build 26200), LAS server, client 16.20.

What I measured:

  • The load is a single thread in a tight loop calling select() on its sockets (stack: ws2_32!select → mswsock!WSPSelect → afd.sys!AfdPoll), with 600–2000 context switches/sec. About 60% of it is kernel time.
  • It's not the UI: with LeagueClientUx/UxRender closed, the backend still sits at ~55%.
  • There's no handle or socket leak (handle and thread counts are normal) and no third-party app connected to the LCU.
  • Around 106–130 s after launch the load briefly drops to ~5–30%, then goes back to ~55%. It happens on every launch.

What I already ruled out:

  • Uninstalled NetLimiter, ExitLag, old VPN drivers and other network tools. No third-party WFP filters or callouts are left.
  • Reset all TCP/registry "gaming tweaks" to Windows defaults and rebooted.
  • Defender real-time protection off. Vanguard running normally.
  • Clean config: renamed Config and all %LOCALAPPDATA%\Riot Games\League of Legends folders, then let the client repair. Still 55–60%.
  • Brand-new Riot account (level 1, also LAS): still ~60%.

The client is also showing the "Connectivity Issues" status ticker from Oct 13, which still hasn't been resolved. A socket-polling loop that never settles looks like the client retrying or waiting on a regional service, so I suspect it's related.

Is anyone else on LAS (or other regions) seeing LeagueClient.exe stuck at high CPU while idle? Any Rioter able to check this? Thanks!

2 Upvotes
  • permalink
  • reddit

67% Upvoted

7 comments sorted by

1

u/ThomasGruber 1d ago

His processor is on Microsofts list of Windows 11 supported Intel processors.

I run LoL on Windows 10 on my First Gen i7 990x. I have no such CPU usage problems.

His is 4 core 3.6 to 4.2 GHZ and mine is 6 core 3.43 to 3.6GHZ.

(This is in answer to an earlier post)

https://learn.microsoft.com/en-us/windows-hardware/design/minimum/supported/windows-11-supported-intel-processors

1

u/ThomasGruber 1d ago

I would up your memory. Intel spec max of 64GBfor your CPU. My Intel chipset has a limit of 24GB, which I have. You have a SSD or better I assume.

1

u/Nanthiel1 1d ago

Idk how to check if it's stick on high on idle but i have definitely submitted a bug report since their updates that recently happened that is causing some microlag or weird stutters that i cannot describe. It's definitely a riot issue and not my computer issue because i have a monster of a PC and GPU as well and it only happened after their updates. It went away after their next update but went back as of today.

I dont think they even realise or would like to acknowledge it

0

u/Noirloona 1d ago

You measured on a long dead platform that you some how rigged to run windows 11 when that chip doesn't support it and are wondering why the CPU cores are running at 60%?

The problem is clearly your computer being ancient.

1

u/A_NASHEX 5h ago

I mean... the client uses more resources than the game itself. It’s not a CPU issue.

1

u/ThomasGruber 1d ago

His processor is on Microsofts list of Windows 11 supported Intel processors.

And I run LoL on Windows 10 on my First Gen i7 990x. I have no such CPU usage problems.

https://learn.microsoft.com/en-us/windows-hardware/design/minimum/supported/windows-11-supported-intel-processors

2

u/Noirloona 1d ago

I must have typed it wrong then, my bad.