Diablo® III

[Solution] FPS Stuttering/Latency Fix

Posts: 4
Diablo 3 use to freeze for a few seconds when I got a lot of new monsters on the screen. I thought it was a video card bug. But no video card setting adjustments had any effect on the stuttering. Then I noticed it could also happen just opening a chest with everything cleared. Meaning it happened when my client needed to connect with the server.

I remembered Blizzard also had a problem in Wow and the Leatrix Latency cut my latency by more than half. After installing the latest version of the fix, my stuttering went from a few seconds to a fraction of a second. So I still get a little stutter, but usually not long enough to get killed.

Leatrix Latency Fix:
Reply Quote
I get off work in 45 minutes, if this works when I gethome I will buy you oh so many beers
Reply Quote
Posts: 4
How It Works

Online games generally use the TCP protocol which requires that network segments sent to your computer be acknowledged in order to provide a reliable connection.

Windows bundles these acknowledgements together and sends them in pairs. While this is an efficient way of dealing with them generally, the inevitable delays caused by the bundling process increase latency considerably.

This is because when Windows queues up an acknowledgement in order to bundle it with the following one, the game server has to wait for the acknowledgement timer to expire before sending new data.

Leatrix Latency Fix removes the acknowledgement bundling process so that an acknowledgement is sent immediately for every segment that's received. This produces a significant reduction in latency as there is no longer a delay before new data is sent to your computer.

In a normal networking environment, you would prioritise network efficiency over latency and use the Windows defaults, but in online games the opposite is true and you want the lowest latency you can possibly get.

Typical Scenario

If you could listen to a conversation between your computer and the game server, this is what you would hear.

Before Leatrix Latency Fix is installed:

Server: "Ok computer, I just sent a data packet over to you, got it?"
Your computer: ...
Server: "Come on, answer me! I don't have all day! Stop wasting time!"
Your computer: ...
Server: "Ok, forget it, I've waited long enough, sending another one over! Got it?"
Your computer: "Yep, got that one, also got the one you sent before, thanks."
Server: "Well, why didn't you acknowledge the first one when I sent it? I was waiting ages!"
Your computer: "Sorry, I'm just trying to make the network more efficient by bundling the acknowledgements together in pairs. This is how I'm setup by default."

After Leatrix Latency Fix is installed:

Server: "Ok computer, I just sent a data packet over, got it?"
Your computer: "Yep, send the next!"
Server: "That was fast! Ok, here's another, got that?"
Your computer: "Yep, send the next!"
Server: "Wow! What an improvement! Now that's more like it!"
Your computer: "Yep, it's certainly keeping me on my toes, thanks!"
Reply Quote
Posts: 56
So it basically disables Nagling? That can have downsides for other games by the way.
Reply Quote
most other games use udp, not tcp. ;o

but the assumption is fundamentally wrong. the server doesn't send single packets. it sends multiple packets, without waiting for a response. the server doesn't expect a response after every packet. this is just the way tcp/ip works. sending a TCP ACK after every packet degrades network performance.

now if someone at blizzard could confirm that their servers aren't in some unexplicable way setup to wait for an ACK after every packet...

otherwise see 'tcp window size'.
Reply Quote
"Leatrix Latency Fix" doesn't do anything for my Latency which is about 70ms but it DOES seem to reduce the vomit inducing stuttering which was driving me crazy to a tiny stutter which is barely noticeable, but I require more time to test.
Reply Quote
Posts: 63
Did not work for me.
Reply Quote
Some suggestions here might help you out:
Reply Quote
after doing a bit more research, it seems this would possibly only fix issues for people with older routers.

in other words, its a client-side fix.

it has nothing to do with the router/server congestion issues at bliz.
Reply Quote
The technical reasoning behind this "fix" is flawed. Once the TCP connection is established, more frequent ACKs will not affect the server's ability to send data to the client or the speed/latency at which it does so. That's simply not how TCP works.

This is snake oil, pure and simple.
Reply Quote
Does not work
Reply Quote
Is there any other programs that will make the same tweak as latency fix?
Reply Quote
no, this is only a 'possible' fix if you have a really old and crappy router, which doesn't support ECN.

i know it says don't post external links, but here is a test from microsoft to see if it does:

it must be run in internet explorer 6 or later, not other browsers.

the value you are looking for is 'Traffic Congestion Test' = Supported.


there is no way this does anything in the real world. it actually makes your TCP connections WORSE.

the better solution would be to just buy a NEW router, 20-30$ instead of messing with your TCP connections.
Edited by betatrash#1974 on 5/22/2012 10:17 AM PDT
Reply Quote
Posts: 4
After using it for longer, I apologize for using the word solution in the title. "Partial improvement" would have been more accurate. When I first installed this and used it for an hour, my stutters had all dropped from a few seconds to a fraction of a second. However after using it for a few days, I still occasionally get stutters that last a few seconds, but they happen much less often.
Reply Quote
thats probably because the servers were performing better last night. also, what make/model of router do you have? and have you visited the microsoft link i posted to test your router for ECN?
Reply Quote
If you are connected directly to a modem would this do anything?
Reply Quote
Posts: 4
My router is a Cisco DPC3825
Reply Quote

Please report any Code of Conduct violations, including:

Threats of violence. We take these seriously and will alert the proper authorities.

Posts containing personal information about other players. This includes physical addresses, e-mail addresses, phone numbers, and inappropriate photos and/or videos.

Harassing or discriminatory language. This will not be tolerated.

Forums Code of Conduct

Report Post # written by

Explain (256 characters max)