Hi Rowby

it all depends on the power of your machine in terms of CPU, GPU and disks.

Obviously it makes sense to deactivate all unnecessary services. My switchers are dedicated to production, I don't even install softwares like Office, Adobe or any other software that is not required in the workflow on them. No dropbox or onedrive either... I have other regular laptops with all these things...

When you have a pretty decent GTX board, the CPU is usually not really sollicited, especially not by PNGs even with transparency. In terms of quality, you have better results with a PNG with alpha than with a jpeg with chroma. You should not be worried to use PNG.

I'm not sure the video codecs when you only play standard videos in your production is really an issue. But you could have trouble when reading high bitrates videos like prores or VC3 or uncompressed videos for sure. It can affect the CPU badly especially if you don't have SSDs (or multiple hard disks). Try not to record on the same disk as you read from (I always have a dedicated disk for recording and another one for every files used as sources).

vMix makes an extensive use of GPU so even for complex projects with a lot of cameras and a lot of files, it usually does not use a lot of CPU. Except when using USB capture boards...

And as long as you use the hardware encoder (nvenc) for streaming and recording you should not have CPU problems.

My 2 cts...

What codec ?

Generally I would have thought an I frame only codec, such as Prores, Mjpeg, DNX or sequential files would be quicker to decode but you then have the penalty of higher bitrates but in the world of SSDs this is less of an issue.

This is how it works with editing apps. Avid with H264 is a bit sluggish but it's fine with DNX.