What is Input Lag & How Can You Fix/Test It?

What is Input Lag & How to Fix Input Lag

There are many things that can ruin a gaming experience—low framerates, high network latency, a squeaky chair—but perhaps one of the most common (and most annoying) problems is input lag.

While input lag might not bother you if you’re sitting a few feet from your screen with a gamepad in hand, if you’re playing first person shooters with a mouse and keyboard, it can become a pain very quickly.

When you’re lining up the perfect headshot only to miss because the game registers your mouse click a second too late, input lag can mean the difference between winning and losing a match.

Perhaps even more frustratingly, there are several things that can cause input lag, making it hard to diagnose. But it’s possible to fix input lag and doing so doesn’t always have to cost an arm and a leg.

What is Input Lag?

Input lag, also known as ‘system latency’, refers to the time between your peripheral inputs and the corresponding game actions being outputted on-screen.

For instance, if you press your mouse button to make your in-game character shoot their weapon, input lag would be the time taken between the mouse press and your character visibly shooting on-screen.

Everyone has some level of input lag, it’s just that hopefully the latency is so low that it’s imperceptible. It occurs because there’s a whole chain of things that must happen between your mouse click and your character shooting their weapon.

  1. First, your peripherals must process your input and send this data to your motherboard and then to your CPU.
  2. Your CPU must then process this input and instruct the graphics card to render a certain game state based on this new information, which means transmitting the instruction via the motherboard to the graphics card.
  3. Your GPU then needs to store the information in a render queue, render the new game frame, and send it to the display for output.
  4. Finally, your monitor needs to display the new game frame on-screen, and it can only do this when the display ‘refreshes’.

All of these things happen between you pressing ‘shoot’ and your in-game character visibly shooting on-screen.

Any one of these steps can cause high input lag. Especially egregious input lag usually has peripherals or the monitor as the culprit, but GPU and CPU processing capabilities and the motherboard’s data transport capabilities can play a part.

Do you have Input Lag or Network Lag?

Sometimes network lag can be mistaken for input lag, and vice versa. Network lag is when data takes a long time to be sent or received over your network and the internet.

When gaming online, this might mean that your inputs take a while to translate into game actions, because there’s a delay between these inputs and the server registering and processing them or sending the resulting game state back to you for your PC to display.

Ethernet Cable

Online games have some things happening ‘client side’ (on your end) and other things happening ‘server side’ (on the game server’s end). If the action you’re trying to perform is one that requires interaction with the server for it to register—say, opening a loot box that exists for everyone on the server—then network lag might be the culprit of any visible delay.

If you’re suffering from network lag, then likely only some game actions will be delayed. Maybe you’ll be able to move and shoot without any visible delay, but opening doors will be delayed. Or, as is most common with network lag, your gun will shoot with no delay but there will be delay between these shots and when they register as having hit the enemy.

If you’re suffering from input lag, on the other hand, every game action caused by an input from the peripheral in question will be delayed—for example, your character around, shooting, and interacting with in-game objects.

If you still can’t tell, online games should tell you your ‘ping’, which is how much network latency there is between your system and the game server. If your ping is high, the delay you see is most likely due to network latency, not input lag.

Also Read: What is A Good Internet Speed for Gaming?

What Causes Input Lag?

Input lag can be caused by any part of the chain leading from your key or mouse press to the corresponding game action being displayed on-screen. It’s most often caused by the peripherals or display, but it can also be caused by the CPU or GPU, or the transporting of data between all these things.

Mouse and Keyboard

If you have input lag, the culprit might be your mouse or keyboard. Apart from your monitor, your peripherals are most likely to be what’s causing delay.

Wireless mice and keyboards usually have more delay than wired mice and keyboards, but in recent years wireless technology has improved enough that the delay on the best wireless gaming mice like the Logitech G Pro X Superlight is imperceptible.

MasterSet MS121 Keyboard Mouse Combo

If you have an old wireless mouse or keyboard, or a cheap one that’s not designed for gaming, then this might be the cause of your input lag, because it can take a long time for inputs to travel wirelessly to your PC if the wireless technology in question isn’t very good.

But even some wired peripherals can suffer from input delay. One thing that can cause both wired and wireless mouse delay is a low polling rate, which is how many times per second your mouse communicates with your PC. Grabbing a gaming mouse capable of 1,000Hz polling should help eliminate input lag if your mouse is the culprit.


Inputs from your peripherals are sent via the motherboard to your CPU. Your CPU then takes these inputs and decides what to instruct your GPU to render.

For example, it might tell the graphics card to render the door opening. But the CPU’s processing might also involve other game changes—perhaps your ‘door opening’ stat simultaneously increases, for example. Once it’s computed what to do, it sends an instruction out to the GPU telling it what to process and render.

The longer it takes your CPU to compute all this, the longer the delay between your input and the corresponding game action being displayed on-screen.

However, even most budget gaming CPUs these days shouldn’t cause noticeable input lag in most games. But if your CPU is particularly slow, it might cause input lag in CPU-intensive games like simulation games or 4X games like Civilisation VI.

Graphics Card

After your CPU receives peripheral input data, it tells your GPU what new game state it should render based on this input. The GPU in your graphics card must then render this game state and send the render data out for your monitor to display.

Graphics Card

The longer your graphics card takes to render each frame, the bigger the delay between your input and the corresponding game action being displayed on-screen.

As such, if your graphics card is slow—or if the game is poorly optimised for quick rendering—the more likely you are to suffer input lag because of this. In other words, higher FPS should reduce input lag, providing your monitor’s refresh rate is high enough to keep up with it.


Your peripherals’ inputs travel via USB to your motherboard, and then via your motherboard’s PCIe lanes to the CPU and graphics card, so if your motherboard is particularly slow at transmitting data this can cause input lag.

While USB and PCIe lane generations can affect the speed of large data transfers—such as to and from SSDs—it’s unlikely to directly affect input latency. This is because mouse and keyboard inputs use such little data bandwidth that wider USB and PCIe bus bandwidths likely won’t speed up transfers. And USB 2.0 allows for over 1,000Hz polling, so polling frequency shouldn’t be an issue either.

The only way that a modern motherboard is likely to be the direct culprit of input lag is if it’s faulty—if it has a faulty USB port or PCIe lane, for instance.

If the motherboard isn’t faulty, it might still indirectly cause input lag, however, by bottlenecking the data transfer between the CPU and GPU. If your peripheral input data is bundled in with other game instructions, then a slower motherboard data bus (PCIe) speed might impact how long it takes this data to reach the GPU for rendering, thereby increasing input lag.


Apart from your peripherals, your display is probably the most likely culprit of input lag. After your monitor receives render data from your GPU, it must turn this data into the visible pixels on your screen.

Your monitor displays a new frame with each ‘refresh cycle’, and how many cycles it performs per second is called its ‘refresh rate’. Many monitors still have a 60Hz refresh rate, but these days they are increasingly defaulting to 75Hz at the budget end, and extend all the way up to 360Hz at the high end. The higher your refresh rate, the less likely you are to suffer input lag.


Apart from its refresh rate, a monitor’s internal hardware can influence how much input delay you experience. How a monitor is built can affect its response time, for instance, which is how quickly your monitor can make pixels change from one colour to another.

Even if you have a high refresh rate, if your monitor’s response time is slow it can give the appearance of input lag, as it’ll take more time for your game state to visibly change because of the delay between pixels changing colour. This causes a ‘ghosting’ effect on-screen, but if it’s particularly bad it can feel akin to input lag.

Manufacturers usually list monitors’ response times on their spec sheets, but these can sometimes be deceptive. Nothing beats checking out reviews online for first-hand, practical analysis of a monitor’s response time.

Mouse and Keyboard Drivers

For your PC to use your peripherals correctly, effectively, and efficiently, it must use drivers. A driver is software that helps a component communicate and interact properly with your operating system and applications.

If you don’t have the correct drivers installed—for instance, your motherboard chipset and gaming mouse drivers—then your operating system might not make full and effective use of your peripherals, leading to input lag.

Driver conflicts can also cause input lag. If another driver is interfering with your gaming mouse’s driver, this can sometimes cause problems, including input lag.


VSync is a technology that you can enable in games to prevent screen tearing. Screen tearing occurs when your monitor’s refresh rate isn’t synced with your framerate, so it draws a new frame to the screen before finishing drawing the previous one. VSync eliminates this by limiting your framerate and ensuring it’s synced with your framerate.

But because it limits your framerate and prevents rendered frames from being drawn to your screen until the monitor has fully displayed the previous one, VSync can delay the time between when a frame is ready to be drawn and when the monitor draws it. This can increase overall system latency and cause input lag.

This is more of a problem with VSync than other technologies used to combat screen tearing. Gsync and FreeSync, for example, shouldn’t cause as much input delay as VSync, but not all monitors support these technologies.

Is there an Input Lag Test?

One way to test input lag is to point a high-speed camera at both your mouse and monitor, with an LED hooked up to your mouse button switch. This way, you can measure the video frames between your mouse press LED and your gun firing in game.

Another way is to use NVIDIA’s Latency Display Analysis Tool (LDAT), a piece of hardware that somewhat automates this process for you. You hook it up to your mouse switch and point the sensor towards the part of the screen that will display a muzzle flash when you shoot, then connect it to your PC via USB and run the LDAT software. Once you’ve done this, LDAT should tell you your latency when you shoot.

Finally, if you have a GSync monitor that supports it, you can use the monitor’s built in NVIDIA Reflex Latency Analyzer. Simply connect your monitor to your PC and connect your mouse to your monitor. Then, in your monitor’s settings, set the Analyzer’s analysis window to cover where your gun’s muzzle flash will appear. When you shoot, it should tell you your system delay.

While these latency tests aren’t the simplest to perform, you shouldn’t need to use them to diagnose bad input lag. If you’re suffering from bad input lag, you should be able to see and feel it while gaming.

How to Fix Input Lag

While fixing input lag might sometimes require upgrading your hardware—usually your peripherals or your monitor—there are often ways to fix it that don’t require spending any money.

1. Update and Reinstall your Drivers

If you have input lag, probably the first thing you should try is updating your drivers. Occasionally Windows or other updates can roll out that mess with mouse drivers, and manufacturers will scramble to create new drivers that fix these issues. So, keeping on top of your driver updates can sometimes resolve high input lag.

If just updating your drivers doesn’t solve it, you should try reinstalling all your drivers, ensuring that you only install drivers that you need. Sometimes input lag is caused by one driver conflicting with another—perhaps at some point you accidentally installed another mouse driver that you don’t need. Removing all your drivers and reinstalling only those that you need should fix this.

2. Disable VSync

If you play with VSync enabled in-game and you suffer from input lag, you should try disabling VSync to see if it resolves the issue.

VSync can cause input lag because, to fix screen tearing, it adds delay between your GPU rendering frames and these frames being displayed on the screen. If you have a GSync or FreeSync monitor, try enabling these instead of VSync.

If you don’t have a GSync or FreeSync monitor, you might have to choose between either no screen tearing and input lag, or screen tearing and no input lag. In my experience, however, screen tearing is far less annoying than input lag, so disabling VSync might be a good solution.

3. Enable NVIDIA Reflex or AMD Anti-Lag

One thing that can cause input lag is your GPU’s render queue, which is where your GPU stores instructions for what frames to render. The bigger the queue, the more frames it has waiting to render and the longer you have to wait before your input translates to on-screen action.

NVIDIA Reflex is a technology that attempts to reduce input lag by eliminating the render queue, allowing the GPU to render frames as soon as the CPU tells it to. NVIDIA GeForce GTX 900-series cards and above can use Reflex in supported games, and it can be enabled in these games’ settings menus.

If the game you’re playing doesn’t support NVIDIA Reflex, you can go to your NVIDIA control panel and toggle ‘Low Latency Mode’ to ‘Ultra’ under the ‘Manage 3D Settings’ tab. This attempts to eliminate the render queue on the driver (rather than game engine) level and should work almost as well as NVIDIA Reflex.

If you have an AMD card, you can enable AMD Anti-Lag for individual games via the Radeon control panel. This works in a similar way to NVIDIA’s Low Latency Mode, reducing the number of instructions queued and thereby reducing delay.

4. Cap your Framerate

Capping your framerate can reduce input lag in some games and some scenarios.

If your GPU is under 100% utilisation while gaming, capping your framerate to a little lower than your GPU is capable of outputting should reduce GPU load and allow it to process and render frames more quickly. If your GPU is handling things at lower than max utilisation, however, capping your FPS probably won’t reduce input delay very much.

Also bear in mind that setting your frame cap too low can have a negative impact on input latency. Lower FPS means more time between each frame being displayed on screen, which means more input lag.

Striking a balance between GPU utilisation (via an in-game frame cap) and a high framerate (by not capping your FPS too low) is key.

5. Lower your Graphics Settings

Providing it doesn’t max out your GPU utilisation, increasing your framerate should reduce input lag, because more frames being rendered each second means less potential time between each frame—and the game actions—being displayed on screen.

As such, lowering your game’s graphics settings—especially your resolution—can help increase your FPS and reduce input lag. If you don’t know which settings to change, you can check out some of our game settings guides, such as this one that shows you the best settings for Fortnite.

6. Try a Different USB Port

While it isn’t a likely cause, it could be that your input lag is being caused by a faulty or poorly performing USB port. If your USB port isn’t working as intended, it might be delaying the input from your peripheral to your system.

Try plugging your peripherals into different USB ports, preferably ones on the back of the tower, connecting directly to the motherboard, rather than via the tower’s front panel ports.

7. Upgrade your Hardware

If you’re still suffering from input lag and you’ve tried all the above, one of your components might be the culprit. Most likely, if your input delay is very noticeable, it will be a problem with your mouse or keyboard or your monitor.

If your monitor has a low refresh rate and a high response time, it could be this that’s causing delay. Consider choosing a monitor that’s known to have no latency issues and that has a high refresh rate.

If your monitor already has a low response time, high refresh rate, and tests well for latency in online reviews, then it’s more likely that your mouse or keyboard will be the culprit. Look for a mouse that’s known to have a great sensor, high polling, and, if it’s wireless, great wireless connectivity, such as via Logitech’s LIGHTSPEED technology.

Finally, while this is rarely the culprit, if you have exceptionally old and slow hardware—motherboard, CPU, GPU—then this could be causing input lag, as frames likely aren’t being churned out and drawn to the screen fast enough to keep up with your inputs. In which case, upgrading to any modern, midrange gaming CPU and GPU should improve your input latency.

Jacob Fox

Jacob's been tinkering with computer hardware for over a decade, and he's written hardware articles for various PC gaming websites. Outside of the wonderful world of PC hardware, he's currently undertaking a PhD in philosophy, with a focus on topics surrounding the meaning of life.

Tech Guided is supported by readers. If you buy products from links on our site, we may earn a commission. This won't change how much you pay for the products and it doesn't influence our decision in which products we recommend. Learn more

Leave a Comment

This site uses Akismet to reduce spam. Learn how your comment data is processed.