You can see it in my post...NVIDIA Geforce RTX 3060 Ti, with studio driver version 526.98 from Nov 16th. So it is two days old driver.

To maybe give some help we need the MediaInfo of those used sourcefiles.
To give those in the right way follow this link: https://www.vegascreativesoftware.info/us/forum/faq-how-to-post-mediainfo-and-vegas-pro-file-properties--104561/

F

To maybe give some help we need the MediaInfo of those used sourcefiles.
To give those in the right way follow this link: https://www.vegascreativesoftware.info/us/forum/faq-how-to-post-mediainfo-and-vegas-pro-file-properties--104561/

Format                                   : MPEG-4
Format profile                           : Base Media / Version 2
Codec ID                                 : mp42 (mp42/avc1/niko)
File size                                : 396 MiB
Duration                                 : 11 s 11 ms
Overall bit rate mode                    : Variable
Overall bit rate                         : 301 Mb/s
Encoded date                             : UTC 2022-11-08 06:35:51
Tagged date                              : UTC 2022-11-08 06:35:51
NCDT                                     : NCTG

Video
ID                                       : 1
Format                                   : AVC
Format/Info                              : Advanced Video Codec
Format profile                           : High@L6.1
Format settings                          : 1 Ref Frames
Format settings, CABAC                   : No
Format settings, Reference frames        : 1 frame
Format settings, GOP                     : N=1
Codec ID                                 : avc1
Codec ID/Info                            : Advanced Video Coding
Duration                                 : 11 s 11 ms
Bit rate mode                            : Variable
Bit rate                                 : 299 Mb/s
Width                                    : 3 840 pixels
Height                                   : 2 160 pixels
Display aspect ratio                     : 16:9
Frame rate mode                          : Constant
Frame rate                               : 59.940 (60000/1001) FPS
Color space                              : YUV
Chroma subsampling                       : 4:2:0
Bit depth                                : 8 bits
Scan type                                : Progressive
Bits/(Pixel*Frame)                       : 0.601
Stream size                              : 392 MiB (99%)
Encoded date                             : UTC 2022-11-08 06:35:51
Tagged date                              : UTC 2022-11-08 06:35:51
Color range                              : Full
Color primaries                          : BT.709
Transfer characteristics                 : BT.709
Matrix coefficients                      : BT.709
Codec configuration box                  : avcC

Audio
ID                                       : 2
Format                                   : AAC LC
Format/Info                              : Advanced Audio Codec Low Complexity
Codec ID                                 : mp4a-40-2
Duration                                 : 11 s 8 ms
Bit rate mode                            : Constant
Bit rate                                 : 256 kb/s
Channel(s)                               : 2 channels
Channel layout                           : L R
Sampling rate                            : 48.0 kHz
Frame rate                               : 46.875 FPS (1024 SPF)
Compression mode                         : Lossy
Stream size                              : 344 KiB (0%)
Language                                 : English
Encoded date                             : UTC 2022-11-08 06:35:51
Tagged date                              : UTC 2022-11-08 06:35:51
 

That footage requires extreme computer processing power -- which most mortals don't possess.

Videos play smoothly in VLC, 

Playback from the compressed file in a player, and decoding to raw bits for nonlinear editing are two different things. Vegas is being asked to process 1,605,333,333,336 calculations per second, approximately ;?)

Search the word "Proxy" on this forum. If that doesn't help, upload a very short actual sample of your footage to Drive or Dropbox, and post a link here.

This is not hardware problem, but purely Vegas software issue, since footage plays smoothly in both VLC player and the Adobe Premiere Pro without any issues.

That data rate may be too much for the NVIDIA decoder in Vegas. (4K60 @ 300MBps) Red indicates a problem with the GPU. I'd make proxy files and put the rest of the settings back to default..

This is not hardware problem, but purely Vegas software issue, since footage plays smoothly in both VLC player and the Adobe Premiere Pro without any issues.

@Roman-Novotny You could upload to a file sharing site so others can try and check for same result

Roman,

I had prepared a lengthy technical explanation for you, which would never get read or the implications understood. Suffice it to say you have stated a common misconception.

@RogerS and @Former user are entirely correct, so I strongly encourage you to follow their advice.

@Musicvid

[Techno-philosophical musings on a bright sunny day when I could be doing something useful]

Why on God's Green Earth does a camera company record UHD 4:2:0 video at 300 Mbps while recording the audio with a lossy codec (AAC LC) at 256 Kbps?

[/Techno-philosophical musings on a bright sunny day when I could be doing something useful]

@Roman-Novotny

1. Use proxies.
2. Go outside to see the sun since it goes down earlier this time of year north of the equator.

Why on God's Green Earth does a camera company record UHD 4:2:0 video at 300 Mbps while recording the audio with a lossy codec (AAC LC) at 256 Kbps?

Answer: "Because we can."

Question: How can we deliver 4k video at 300Mbps 60p

Answer: We can't.

Question: Then why shoot it?

Answer: Because we can.

I was looking at the MediaInfo of that file. Shot in 4:2:0 8bit at a bit rate of 300Mb/s. I would think it would be at least 4:2:2 10bit. I wonder if there is any visible difference between a lesser setting of 4K in the camera (100Mb/s) and the higher bit rate.

visible difference

Nope. And even though 100Mbps AVC is still overkill, it will preview better on a fast system. Still don't understand the aversion to proxies.

No aversion to proxies here! Just wondering about the "why's" so to speak.

@Roman-Novotny How do you feel about Prores HQ? Looks to have a base bitrate around 900Mb/s for 4K60, this file is 1800Mb/s. Obviously the negative is file size, reducing amount of video on memory card, and increasing time of transfer, as well as storage. You didn't mention which exact camera you have but this info for Z9

It plays and scrubs well.

No aversion to proxies here! Just wondering about the "why's" so to speak.

I knew that, just a general comment. 😉

Dear all, thanks to all for comments. It is obvious that for Vegas this footage is simply too much. Luckily there are other tools on the market, that can handle it without any issues and without constant crashing....