The "Render Time" display at the bottom of vMix indicates how much of your computers' graphics cards time is being used to render each frame of your production.

It is displayed in milliseconds, so if your production is 30 frames per second (approx 33ms per frame), a render time of greater than this will result in dropped frames.

 

There are a number of potential factors that can cause higher than expected render times which are outlined below:

 

You may be exceeding the maximum capabilities of the graphics card installed.
For example, integrated graphics such as from Intel can only process a small number of inputs at a time, whereas a very high end graphics card such as the NVIDIA GeForce 1080 Ti should be able to handle almost anything you throw at it.

Our reference systems page provides a guide of various systems and graphics cards along with how many vMix inputs you can expect to use within a single production.

 

 

This feature can substantially reduce the graphics performance in apps like vMix and should be disabled or uninstalled completely.

To disable Share (previously known as ShadowPlay), see the following article:

 

Regardless of the speed of the graphics card, at a certain point other system bottlenecks will be reached when using a very high number of inputs.

The best thing to do in this situation is reduce the number of inputs in vMix. In particular reducing the number of video clip inputs can help substantially. The vMix List input
can be used to group many video clips as a single input and is highly recommended instead of adding each video clip separately.

 

NOTE: If you have a graphics card with 3GB+ or memory (such as a GeForce 1060 or higher) you can enable "High Input Performance Mode" in vMix under Settings -> Performance
to allow more inputs to be used without increasing the Render Time.

 

The graphics card needs to be installed in the fastest PCI Express slot on the motherboard where possible.

Usually this is the longest slot that is closest to the CPU (I.E towards the middle of the motherboard)
The slot should be at least x8 in speed. Do not install a graphics card in a x1 or x4 slot.

 

You can confirm the slot is fast enough by running the GPU-Z utility which can be downloaded below:

Where it says "Bus Interface" it should say at least x16 or x8. If it is lower than this check the motherboard documentation for the correct slot to use.

 

Using more than a single graphics card will substantially reduce performance. Remove any extra graphics cards and make sure all screens are connected to a single graphics card and not to the video ports
on the motherboard itself.

 

A driver on the system may be interfering with the graphics card. To check for this, run the LatencyMon program while vMix is running with high Render Times and it should be able to determine which driver is at fault:
http://www.resplendence.com/latencymon

 

 

If you have configured the vMix application (vmix64.exe) in the NVIDIA control panel with settings like anti-aliasing, these will cause severe performance issues and should be disabled.

To reset everything back to default:

1. Open the NVIDIA Control Panel

2. Go to Manage 3D Settings
3. Go to Program Settings tab and select vMix from the dropdown list. (If there is no vmix on the list then this guide does not apply)

4. Click Remove
5. Click Apply bottom right hand corner.
6. If this is a laptop, run the steps in the guide below to configure vMix to use the graphics again with default settings:

 

 

If the computer is under very high CPU load (>70%) then this will also impact GPU performance and as a result, render times.
Check Task Manager in Windows to see which applications are using the most CPU.
If vMix is one of the apps using a lot of CPU, you may need to downscale your vMix production such as inputs, recording and streaming quality until CPU usage as at a more reasonable level. (ideally 60% or lower on average)

See the Optimising Performance guide for tips on getting the most out of the CPU.